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Lethal Tides: Mary Sears and the Marine Scientists Who Helped Win World War II
"Magnificently researched, brilliantly written, Lethal Tides is immensely entertaining and reads like an action novel. Catherine Musemeche has brought to life the incredible work of the scientists and researchers who made such a remarkable contribution to America’s war effort in the Pacific theater during WWII.” —Admiral William H. McRaven (U.S. Navy, Ret.), #1 New York Times bestselling author of Make Your Bed and The Hero Code Lethal Tides tells the story of the virtually unknown Mary Sears, “the first oceanographer of the Navy,” whose groundbreaking oceanographic research led the U.S. to victory in the Pacific theater during World War II. In Lethal Tides, Catherine Musemeche weaves together science, biography, and military history in the compelling story of an unsung woman who had a dramatic effect on the U.S. Navy’s success against Japan in WWII, creating an intelligence-gathering juggernaut based on the new science of oceanography. When World War II began, the U.S. Navy was unprepared to enact its island-hopping strategy to reach Japan. Anticipating tides, planning for coral reefs, and preparing for enemy fire was new ground for them, and with lives at stake it was ground that had to be covered quickly. Mary Sears, a marine biologist, was the untapped talent they turned to, and she along with a team of quirky marine scientists were instrumental in turning the tide of the war in the United States’ favor. The Sears team analyzed ocean currents, made wave and tide predictions, identified zones of bioluminescence, mapped deep-water levels where submarines could hide and gathered information about the topography and surf conditions surrounding the Pacific islands and Japan. Sears was frequently called upon to make middle-of-the-night calculations for last-minute top-secret landing destinations and boldly predicted optimal landing times and locations for amphibious invasions. In supplying these crucial details, Sears and her team played a major role in averting catastrophes that plagued earlier amphibious landings, like the disastrous Tarawa, and cleared a path to Okinawa, the last major battle of World War II.
320 pages, Hardcover
First published January 1, 2022
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604 people want to read
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Displaying 1 - 30 of 76 reviews
September 12, 2022
This book about WW2 and the US Navy and oceanography is not my typical read and I loved this! Reminded me a little of Code Girls, Hidden Figures, etc in the sense of revealing an important story of women’s impact in history in technical roles. More importantly it was easy to follow despite the subject matter and Musemeche clearly researched the heck out of this book and successfully weaved it together for a compelling narrative. I loved learning about this corner of history - I bet they make a movie out of this!
September 6, 2022
Science, biography, and military history are combined to tell the compelling story of an unsung woman who had a dramatic effect on the U.S. Navy’s success against Japan in WWII, by creating an intelligence-gathering juggernaut based on the new science of oceanography. Mary Sears was a marine scientist who, due to her gender, was not allowed to sail on the ocean. Although she worked with the preeminent American ocean scientists of the time, the taboo about women on sailing vessels that sprang from myths like the Odyssey continued well into the mid-20th century. Not content to analyze other scientists’ water samples, Sears had to travel to Peru at the request of their government in order to gather her own samples for analysis. But WWII changed all that. When the war began, the U.S. Navy was unprepared to enact its island-hopping strategy to reach Japan. Anticipating tides, planning for coral reefs, and preparing for enemy fire was new ground for them, and with lives at stake it was ground that had to be covered quickly. Mary Sears’ time had come. The Sears team, the Oceanographic Unit of the U.S. Hydrographic Office, analyzed ocean currents, made wave and tide predictions, identified zones of bioluminescence, mapped deep-water levels where submarines could hide and gathered information about the topography and surf conditions surrounding the Pacific islands and Japan, based on information that was accessed by tireless researcher, oceanographic librarian, Mary Grier. The JANIS (Joint Army Navy Intelligence Studies) reports they developed on each target were considered the most comprehensive intelligence sources available to those planning military operations. In supplying these crucial details, Sears and her team played a major role in averting catastrophes that plagued earlier amphibious landings, like the disastrous Tarawa, and cleared a path to Okinawa, the last major battle of World War II, and worked after the war to assist the military during the occupation of enemy territory.
The book is written in an accessible style for the average reader, but also provides substantial detail for anyone interested in how this facet of intelligence was utilized by the military. It illustrates how a small unit of hardworking Americans, mostly women, worked as a team and rose to the occasion to present the most detailed, best available information for the U. S. war effort in the Pacific.
In 1999, it was announced that the USNS Mary Sears would become the navy’s next oceanographic survey ship. It was launched 17 December 2001. Not bad for a girl who couldn’t get a ride on a boat 60 years earlier.
The book is written in an accessible style for the average reader, but also provides substantial detail for anyone interested in how this facet of intelligence was utilized by the military. It illustrates how a small unit of hardworking Americans, mostly women, worked as a team and rose to the occasion to present the most detailed, best available information for the U. S. war effort in the Pacific.
In 1999, it was announced that the USNS Mary Sears would become the navy’s next oceanographic survey ship. It was launched 17 December 2001. Not bad for a girl who couldn’t get a ride on a boat 60 years earlier.
January 11, 2023
"Because the Federal Government has very little memory, it is generally forgotten that the first oceanographer of the Navy in modern times, was a short, rather shy and prim WAVE Lieutenant Junior Grade. They underestimated the powerful natural force that is Mary Sears."
- Roger Revelle
"Lethal Tides" is yet another example of how big changes are aided by the most dire of circumstances. In it, Musemeche provides a fascinating perspective on (primarily) the pacific theater of WWII and lifts another ridiculously accomplished heroine out of historical obscurity. Mary Sears absolutely deserves the recognition.
The author balances the admittedly rather dull hunt for nautical and oceanographic records and the compiling of recommendations and reports with the more action-friendly results of the same (i.e. amphibious landings) - as well as the appalling casualties when the reports didn't exist or weren't abided by (the author specifically mentions Tarawa and Iwo Jima - the latter, as far as I know, being the only Pacific battle where U.S. casualties outnumbered Japanese ones). This serves the dual purpose of both making the book easier to read, and of providing breath-taking illustrations of the impact of the work done by Sears and her team.
"Your technical knowledge and administrative skill were instrumental in the selection, compilation, and publication of oceanographic data of great value to the Armed Forces of the United States. In your capacity of oceanographer, you were frequently called upon by the Joint Chiefs of Staff to furnish critically valuable information for use in combat operations. Your performance of all these duties was at all times exceptional, and beyond the high standard normally expected."
- Admiral Chester W. Nimitz, post-war commendation to Mary Sears
Nimitz words are a testament to the war-time work of Sears, and made all the more potent by the simple fact that women were not even allowed in the U.S. Navy until well into WWII. They are testament to the incredible dedication and sacrifice Sears lived and exhibited throughout a professional life of continuously bumping into the proverbial glass ceiling - a ceiling she played no small part in pushing ever higher.
"Lethal Tides" is a well-written and absolutely fascinating book. I think it comes out on top in the inevitable comparison with Shetterly's "Hidden Figures," and I'd recommend it to just about anyone!
The only thing that left a bit of a bad taste in my mouth after reading it, was the interesting author choice of explicitly and frivolously feminizing Sears when she's portrayed interacting with male bigwigs. Why? Sears after all, as a woman, struggled with being "othered" her entire professional life. It's not much of a complaint - and I'm clearly nitpicking - but it nonetheless bothered me on more than one occasion. It really doesn't take anything away from this great book though. "Lethal Tides" is absolutely deserving of being bumped up on that tbr list!
September 26, 2022
Catherine Musemeche brings us a compelling true story chock full of "wow--who knew?" information in an accessible narrative style. I was astonished to read about Mary Sears and her hearty band of oceanography nerds, academics, researchers, and librarians in a pre-computer age, wielding index cards, hand drawings, silk handkerchief maps to provide vital information to the Pacific forces. Of course, it's not surprising to learn about the flagrant discrimination women faced in so many realms back then, but that made the story of Mary Sears' grit, determination, leadership, and contributions all the more thrilling.
September 29, 2022
I think a solid four stars.
I listened to the audiobook on Glose. As always, zero stars for Glose’s app.
I appreciated that there is a book about an unsung woman who doesn’t just fill in because a man is unavailable due to wartime constraints, but that she also proves that she’s the best person for the job, regardless of gender. Three cheers for her team’s ability to repeatedly outperform other intelligence groups with their skills.
As an engineer, I wish the book were more technical than it is. I’d have liked to have a better understanding of what the JANIS reports looked like, and how the war planners used them. It kind of felt like there was a side or two to the story that wasn’t told.
(The Harper Collins accompanying PDF had one high-level map showing the Pacific Ocean and Allied progress in the Pacific Theater. I wanted to see what hydrographic/oceanographic detail looks like.)
For this deficiency, and a good story imperfectly told, I dock a star.
I listened to the audiobook on Glose. As always, zero stars for Glose’s app.
I appreciated that there is a book about an unsung woman who doesn’t just fill in because a man is unavailable due to wartime constraints, but that she also proves that she’s the best person for the job, regardless of gender. Three cheers for her team’s ability to repeatedly outperform other intelligence groups with their skills.
As an engineer, I wish the book were more technical than it is. I’d have liked to have a better understanding of what the JANIS reports looked like, and how the war planners used them. It kind of felt like there was a side or two to the story that wasn’t told.
(The Harper Collins accompanying PDF had one high-level map showing the Pacific Ocean and Allied progress in the Pacific Theater. I wanted to see what hydrographic/oceanographic detail looks like.)
For this deficiency, and a good story imperfectly told, I dock a star.
November 22, 2022
Mary Sear’s primary contribution towards WWII war efforts was a series of oceanography reports on different Pacific Islands. These reports were put together by scouring libraries across the world to collect published data on the different areas and then writing up a report on it. Some may ask: “well…how interesting can a story about that actually be?” The truth is there is definitely a limit to how interesting a book about writing reports can be. The good news is that the author of this book accepts this fact (as well as the limited historical records on the topic) and shifts focus to the dramatic amphibious assaults in the Pacific Island hopping campaign.
It’s safe to say that only a portion of this book is actually directly about Mary Sears. The rest is a story of the war in the Pacific with an emphasis on the role of Sears’ reports. Musemeche conveys a message about the importance of the oceanography reports while also delivering a well written short history on the Pacific Island hopping during the war.
My one complaint about this book was the lack of focus on the aid that Sears provided to anti-submarine warfare. Most of the research discussed was about tides and surf and amphibious assaults. While that was all very interesting, I would have liked to see a bit more discussion about the impact of oceanographic intelligence on the battles fought under the sea.
It’s safe to say that only a portion of this book is actually directly about Mary Sears. The rest is a story of the war in the Pacific with an emphasis on the role of Sears’ reports. Musemeche conveys a message about the importance of the oceanography reports while also delivering a well written short history on the Pacific Island hopping during the war.
My one complaint about this book was the lack of focus on the aid that Sears provided to anti-submarine warfare. Most of the research discussed was about tides and surf and amphibious assaults. While that was all very interesting, I would have liked to see a bit more discussion about the impact of oceanographic intelligence on the battles fought under the sea.
September 15, 2022
Mary Sears was a oceanographer, who was passed over for most of her career... but when all the men were drafted or enlisted, her life-long skills were used to help shape and run the new Oceanographic Unit of the Navy Hydrographic Office. This office was responsible for reports used to plan the island hopping campaigns. Tidal data, topography and so much more was included in these reports.
Why I started this book: Title alone had me putting it on hold at the library...
Why I finished it: Fascinating and inspiring. Plus I loved that it was the scholarship and research skills of a ocean librarian that contributed so much to Sears team and their reports. Information is power and having it organized and presented in one location is vital. Sears was very impressive and you can get a lot done if you don't need the credit, and instead focus on the goal and your team.
Why I started this book: Title alone had me putting it on hold at the library...
Why I finished it: Fascinating and inspiring. Plus I loved that it was the scholarship and research skills of a ocean librarian that contributed so much to Sears team and their reports. Information is power and having it organized and presented in one location is vital. Sears was very impressive and you can get a lot done if you don't need the credit, and instead focus on the goal and your team.
September 8, 2022
Interesting story, very reminiscent of Hidden Figures. Her life story and her work in particular with the Navy should be better known and is skillfully recounted. I would love to see this adapted for TV or movie. Cmdr Sears seems to have been both introverted and security-conscious so the story lacks a lot of detail about her own interactions with her naval colleagues. I'm not much of a WWII student, but the author does well explaining the history without overwhelming details.
I found this via Engadget.com
I found this via Engadget.com
November 14, 2022
Finished Lethal Tides: Mary Sears and the Marine Scientists Who Helped Win World War II by Catherine Musemeche, a current work of non fiction about an outstanding oceanographer (and others) who contributed significantly, to WW2 Allied landing/assault strategy, including Okinawa and Normandy. This book profiles a number of unsung heroes, largely women who, although marginalized in pay, rank and authority staffed many important components of war strategy. Sears was a rare commodity in WW2 era America, a woman PHD in Oceanography. She retired from the the Navy at the end of the war as a LT commander, revered by the Joint Chiefs of Staff who appreciated her intelligence and ability to get the job done without drama.
January 25, 2023
Somebody should buy the movie rights to this book. It would make a good movie in the same vein of Hidden Figures. It could begin with the dedication of the Mary Sears research vessel and work, via flashbacks, to the story of her live and the impact of the women at the Oceanographic office on beach landings throughout the war. An easy solid IMDb rating in the upper quartile.
But I get ahead of myself. First the book review.
Musemeche brings to life one of the many backstories of unsung wartime heroes. The story is well told about the development of oceanographic research, its incorporation into military planning, the challenges women faced in careers, and how Mary Sears contributed to each. She isn’t the only hero as Musemeche makes clear. You’ll feel the frustrations and successes Sears and her team, of mostly women, faced in providing current and tidal information ahead of amphibious landings. I think that aspect of the book was most compelling. Reading when their information was used, and helped, or not used.
Have men always been shits towards women? Man, some of the rules dismayed me. Women scientists can’t go out on research ships. Women who attended college were oddities and stereotypes abounded. Career women aren’t pretty. I hope we’re getting better but fear we’ve still got a long way to go.
Weirdest factoid: US government rationing changed fashion and led to shorter skirts on women. The need to conserve fabric caused the rationing department to limit the length of skirts, eliminate pleats, and narrow men’s collars and cuffs. Who would have thought the Feds were fashionistas?
A very solid four-star book.
But I get ahead of myself. First the book review.
Musemeche brings to life one of the many backstories of unsung wartime heroes. The story is well told about the development of oceanographic research, its incorporation into military planning, the challenges women faced in careers, and how Mary Sears contributed to each. She isn’t the only hero as Musemeche makes clear. You’ll feel the frustrations and successes Sears and her team, of mostly women, faced in providing current and tidal information ahead of amphibious landings. I think that aspect of the book was most compelling. Reading when their information was used, and helped, or not used.
Have men always been shits towards women? Man, some of the rules dismayed me. Women scientists can’t go out on research ships. Women who attended college were oddities and stereotypes abounded. Career women aren’t pretty. I hope we’re getting better but fear we’ve still got a long way to go.
Weirdest factoid: US government rationing changed fashion and led to shorter skirts on women. The need to conserve fabric caused the rationing department to limit the length of skirts, eliminate pleats, and narrow men’s collars and cuffs. Who would have thought the Feds were fashionistas?
A very solid four-star book.
September 3, 2023
In 1941 when marine scientist Mary Sears was working in Peru collecting and studying plankton, little did she know that she was destined to direct influential work for a coming war. And it took this war to make the scientific field of oceanography recognize that women can actually do research on a boat and make a difference in war time.
Ironically, Mary Sears who was banned from doing research on board any research vessel at Woods Hole because she was a woman, eventually in 2000 had a survey ship, the USNS Mary Sears, named for her.
During the war, Mary Sears and her fellow scientists and researchers provided information and intelligence on marine conditions, ie, tides, drift, swells, what to expect from the coral islands for the landing of troops on Japanese held islands.
At war's end, after retiring from active service in 1946, she was still barred from the research vessel at Wood's Hole. It was still "men only."
Excellent book! I would read it again. That's one of my criteria for giving 5 stars to a book! That, and I should learn a lot---which I did.
Ironically, Mary Sears who was banned from doing research on board any research vessel at Woods Hole because she was a woman, eventually in 2000 had a survey ship, the USNS Mary Sears, named for her.
During the war, Mary Sears and her fellow scientists and researchers provided information and intelligence on marine conditions, ie, tides, drift, swells, what to expect from the coral islands for the landing of troops on Japanese held islands.
At war's end, after retiring from active service in 1946, she was still barred from the research vessel at Wood's Hole. It was still "men only."
Excellent book! I would read it again. That's one of my criteria for giving 5 stars to a book! That, and I should learn a lot---which I did.
September 18, 2022
WW 2 is a well-worked subject. Here's a story from the fringes. It's actually a very interesting portrait of an extremely effective person, doing her small part to advance the American war effort. The biographical aspects are nicely balanced with the bigger picture. Excellent history!
September 20, 2022
War history has long been a hobby and I always enjoy learning about new people and how they impacted the war in some way. Mrs. Mary Sears is one such person and her and those who worked with her impacted the amphibious operations worldwide during WWII. A worthwhile read.
October 9, 2022
Outstanding biography. In a the books I've read on WWII, I've never come across CDR Mary Sears - this is an important book about a fascinating and brilliant scientist.
February 20, 2023
I’m not the biggest fan of WW2 history, but I picked up Lethal Tides after seeing my Dad read and rate it positively. This is the true story of Mary Sears, an American oceanographer. As a female scientist in the late 1930s, Sears found herself facing the sexism of academia and was frequently passed over for career opportunities. This changed in early 1940s, when all her male coworkers found themselves drafted or enlisted. Left behind, Sears became the head of the newly established Oceanographic Unit of the Navy Hydrographic Office, which was charged with all the data collation and reporting for targets in the Pacific. Her group - which included mostly women - provided the tidal and topography data used in many famous military campaigns, including Iwo Jima and Okinawa.
Unfortunately, while I typically enjoy reading about women in STEM, I found Lethal Tides quite dull at times - after all, this is a book about writing military intelligence reports. I was mostly interested in the first half, which covered Sears' early life and experiences in oceanographic academia. Once we got to the actual military campaigns, I found Musemeche's presentation pretty repetitive. New target, new intelligence report, another scramble for data, rinse and repeat. For some reason, I also thought there would be information on how Sears contributed to submarine campaigns, but this covered exclusively amphibious warfare.
I wouldn't recommend Lethal Tides unless you already know you like WW2 history, and want to learn about the contributions of a forgotten group of stubborn, smart women. Otherwise, I'd probably pass.
Unfortunately, while I typically enjoy reading about women in STEM, I found Lethal Tides quite dull at times - after all, this is a book about writing military intelligence reports. I was mostly interested in the first half, which covered Sears' early life and experiences in oceanographic academia. Once we got to the actual military campaigns, I found Musemeche's presentation pretty repetitive. New target, new intelligence report, another scramble for data, rinse and repeat. For some reason, I also thought there would be information on how Sears contributed to submarine campaigns, but this covered exclusively amphibious warfare.
I wouldn't recommend Lethal Tides unless you already know you like WW2 history, and want to learn about the contributions of a forgotten group of stubborn, smart women. Otherwise, I'd probably pass.
June 28, 2024
I can’t say enough good things about this book. Full disclosure: I’m an oceanographer myself, specifically an operational oceanographer. That means I build and run systems that track ocean conditions not only for scientific research, but also to serve any number of people who work on the ocean and need to understand it better to stay safe.
This is a tale of perhaps the most high-stakes and historically significant instances of applied oceanography. It’s also a tale of how science can and should be deeply integrated into - and respected by - policy processes. That’s a lesson we really need to learn these days: The immediacy of the battles of WWII has given way to the longer term threat of a changing climate, but the stakes are just as high and the need for sound science just as important.
In any case, I can’t recommend this book highly enough to anyone interested in the ocean, history, and the evolution of science.
This is a tale of perhaps the most high-stakes and historically significant instances of applied oceanography. It’s also a tale of how science can and should be deeply integrated into - and respected by - policy processes. That’s a lesson we really need to learn these days: The immediacy of the battles of WWII has given way to the longer term threat of a changing climate, but the stakes are just as high and the need for sound science just as important.
In any case, I can’t recommend this book highly enough to anyone interested in the ocean, history, and the evolution of science.
March 26, 2025
I love women-centered military history! I think the author would have benefitted from talking to present-day oceanographers and military officers so that she could have described more in-depth the science aspect.
April 3, 2023
I continue to be so impressed with the impact that women had on the war efforts through the military. This book has a focused view on the Navy and Marines in the Pacific. Mary Sears is a true hero.
November 11, 2022
Reviewed by Si Dunn for Lone Star Literary Life.
October 5, 2022
I liked everything about this book - the writing, the choice of photos, and definitely the subject matter. Musemeche has a great way of storytelling, and the sections on the war in the Pacific were gripping, with interesting sidebars such as the Montford Point Marines, the Navy Pigeon Loft, and women librarians and scientists who helped the war effort. The notes are full of interesting-looking further reading. Like Musemeche, my pop served in the Navy in the Pacific theater. He never talked about it so I have to find out from books, and I'm glad to have read this one.
September 28, 2022
Lethal Tides was one of the best books I have read this year. It gives great perspective to the value of the oceanographic work done by Mary Sears and her team.
I also owe a personal debt of gratitude. Their work at Iwo Jima probably saved my dad’s life and made my life possible.
Thank you
I also owe a personal debt of gratitude. Their work at Iwo Jima probably saved my dad’s life and made my life possible.
Thank you
September 17, 2022
Excellent work of military history - highly recommend.
September 21, 2022
Outstanding level of research. Important background information for any student of the war in the Pacific during WWII
June 2, 2023
It has become almost cliché to refer to "the unsung heroes" of World War II, but in truth there really were thousands of them, if not millions. This is the story of one: a pioneering woman oceanographer who was already breaking barriers in the 1930s, and who, through her patriotic impulses, interrupted her career to donate her services to the US military and in so doing became an indispensable tool in planning the invasions of Japanese-held islands in the Pacific.
Heading up a team of marine researchers, scientists, draftsmen and women, expert bibliographers, and others, Mary Sears helped produce the Joint Army-Navy Intelligence Studies (JANIS) reports detailing tides, currents, seafloor compositions, coral reefs, wave sizes, and other factors that could influence which beaches were chosen for landings, and the dates of those operations. It quickly becomes clear, reading this exciting account, that had Sears' JANIS recommendations been regularly followed, many American sailors, soldiers, and Marines would have been saved needless deaths; but sadly it happened too often that her unit's recommendations were often ignored by invasion planners in favor of other considerations. That does not, however, diminish their contribution to the US war effort or the many hours of grueling work they spent compiling and summarizing data in such an expert way that soon departments and officers throughout the military were clamoring for their JANIS reports.
Through author Musemeche's narrative we also get to know the amazing Sears as a person too, as well as some of her equally distinguished colleagues. It underscores the fact that even massive, world-enveloping events like world wars are composed, at their lowest level, of humans with their own skills, motivations, and personalities.
This book has a good map of the Pacific war that shows the location of all the major operations that are discussed, and for which Sears' department had to gather information where seemingly none existed--notably in a pre-Internet, pre-search engine world where having someone on staff who knew what obscure publications had the information needed, and where to find them, was absolutely vital. Sears' team also had to produce easily digestible summaries of their findings, including graphics that prefigure today's art/science of "infoporn"--information presented so cleverly and clearly that it is almost entertainment to absorb it.
I mentioned that Sears was a pioneer woman oceanographer, and that is admirably true; but the author spends rather a little too much page space repeating the many injustices against women in the scientific and military worlds in the 1930s and 1940s. It gets a little tiresome after a while. She also throws in a brief discussion of racism against blacks in the military during the war, even though it has absolutely no connection to the story. It comes off as annoyingly white male bashing, which I guess is all the rage these days by any authors who want to be taken seriously by "the right people."
Those flaws don't really detract much from an otherwise excellent biography of a woman who really was an "unsung hero" of the war, and to whom many American fighters who survived the hell in the Pacific may in part have owed their lives.
Heading up a team of marine researchers, scientists, draftsmen and women, expert bibliographers, and others, Mary Sears helped produce the Joint Army-Navy Intelligence Studies (JANIS) reports detailing tides, currents, seafloor compositions, coral reefs, wave sizes, and other factors that could influence which beaches were chosen for landings, and the dates of those operations. It quickly becomes clear, reading this exciting account, that had Sears' JANIS recommendations been regularly followed, many American sailors, soldiers, and Marines would have been saved needless deaths; but sadly it happened too often that her unit's recommendations were often ignored by invasion planners in favor of other considerations. That does not, however, diminish their contribution to the US war effort or the many hours of grueling work they spent compiling and summarizing data in such an expert way that soon departments and officers throughout the military were clamoring for their JANIS reports.
Through author Musemeche's narrative we also get to know the amazing Sears as a person too, as well as some of her equally distinguished colleagues. It underscores the fact that even massive, world-enveloping events like world wars are composed, at their lowest level, of humans with their own skills, motivations, and personalities.
This book has a good map of the Pacific war that shows the location of all the major operations that are discussed, and for which Sears' department had to gather information where seemingly none existed--notably in a pre-Internet, pre-search engine world where having someone on staff who knew what obscure publications had the information needed, and where to find them, was absolutely vital. Sears' team also had to produce easily digestible summaries of their findings, including graphics that prefigure today's art/science of "infoporn"--information presented so cleverly and clearly that it is almost entertainment to absorb it.
I mentioned that Sears was a pioneer woman oceanographer, and that is admirably true; but the author spends rather a little too much page space repeating the many injustices against women in the scientific and military worlds in the 1930s and 1940s. It gets a little tiresome after a while. She also throws in a brief discussion of racism against blacks in the military during the war, even though it has absolutely no connection to the story. It comes off as annoyingly white male bashing, which I guess is all the rage these days by any authors who want to be taken seriously by "the right people."
Those flaws don't really detract much from an otherwise excellent biography of a woman who really was an "unsung hero" of the war, and to whom many American fighters who survived the hell in the Pacific may in part have owed their lives.
December 21, 2023
Lethal Tides tells the story of Mary Sears and the Oceanographic Unit and the Hydrographic Office in the United States Navy during the Second World War. On the face of it, this may sound somewhat dry, but the author has done an excellent job intertwining the work of the office with snippets from the amphibious and submarine operations it supported, and included numerous personal details, that make it an engaging and interesting read. It is an important tale of how details and depth (no pun intended) matter, a lesson well worth reinforcing in today’s shallow “just Google it” age.
It is also a good reminder of just how backwards society was in the first half of the 20th century (and well into the second) in terms of its treatment of women, and an inspiring personal story of Mary Sears’ endeavour to make a mark in a very-much male-dominated field.
It is extremely well-written, with accessible, flowing prose and with one exception (carcinology, the study of crustaceans) describes any terms it introduces well. It was a pleasure to read, and the writing never got bogged down or convoluted. It does not assume any prior knowledge of oceanography, naval history or similar, and adeptly provides background on all the key elements of the story in a way that makes Lethal Tides an excellent read regardless of someone’s prior background or knowledge.
It is also very well-researched. It is clear the author has channelled something of Mary Sears’ work ethic when writing the book, and it is all the better (and a far more valuable contribution to naval and presumably oceanographic history) for it.
There are a few minor slips – a reference to “the Nazi U-boat campaign” in World War I, for example, and at least one instance of casualties being represented as people killed, but these were all minor and not central to the main subject. The treatment of admiral ranks is also inconsistent, and “admiral” is often used as the first reference for any admiral rank (but there are some references to rear and vice admirals as well), but again this is unlikely to be an issue for anyone familiar with the individuals referenced, and not material for those that aren’t interested in that degree of detail.
The book contains reference notes, although instead of footnotes in the text, the notes have no reference at all in the general text, but are instead referred to by page number and a phrase from the text of that page. It does help keep the main text uncluttered, but it does make it a little harder following sourcing. Given the broad audience to which the work is targeted, it’s a sensible approach, and certainly far better than not including reference notes. The book also contains an index, a map of the Pacific showing the Central Pacific amphibious advances, and a 12-page plates section in the middle with a number of well-chosen photographs that highlight the key people in the story and their work.
All up, it’s an excellent read and easily recommended – the details of the operations of the Oceanographic Unit provide a valuable contribution to naval history, and the overall work is an interesting perspective of oceanography and how it relates to naval operations, particularly but not only amphibious landings.
It is also a good reminder of just how backwards society was in the first half of the 20th century (and well into the second) in terms of its treatment of women, and an inspiring personal story of Mary Sears’ endeavour to make a mark in a very-much male-dominated field.
It is extremely well-written, with accessible, flowing prose and with one exception (carcinology, the study of crustaceans) describes any terms it introduces well. It was a pleasure to read, and the writing never got bogged down or convoluted. It does not assume any prior knowledge of oceanography, naval history or similar, and adeptly provides background on all the key elements of the story in a way that makes Lethal Tides an excellent read regardless of someone’s prior background or knowledge.
It is also very well-researched. It is clear the author has channelled something of Mary Sears’ work ethic when writing the book, and it is all the better (and a far more valuable contribution to naval and presumably oceanographic history) for it.
There are a few minor slips – a reference to “the Nazi U-boat campaign” in World War I, for example, and at least one instance of casualties being represented as people killed, but these were all minor and not central to the main subject. The treatment of admiral ranks is also inconsistent, and “admiral” is often used as the first reference for any admiral rank (but there are some references to rear and vice admirals as well), but again this is unlikely to be an issue for anyone familiar with the individuals referenced, and not material for those that aren’t interested in that degree of detail.
The book contains reference notes, although instead of footnotes in the text, the notes have no reference at all in the general text, but are instead referred to by page number and a phrase from the text of that page. It does help keep the main text uncluttered, but it does make it a little harder following sourcing. Given the broad audience to which the work is targeted, it’s a sensible approach, and certainly far better than not including reference notes. The book also contains an index, a map of the Pacific showing the Central Pacific amphibious advances, and a 12-page plates section in the middle with a number of well-chosen photographs that highlight the key people in the story and their work.
All up, it’s an excellent read and easily recommended – the details of the operations of the Oceanographic Unit provide a valuable contribution to naval history, and the overall work is an interesting perspective of oceanography and how it relates to naval operations, particularly but not only amphibious landings.
June 30, 2024
I saw a meme that said something like “When a man turns 50 he has to decide if he’ll be fascinated by the Civil War or WWII.” Yeah, it me. (“It me” is an in-joke in my house.) WWII fascinates me because it only lasted 6 years (literally 6 years and 1 day), yet there’s just so much happening everywhere all the time, and every year we find out like twelve new interesting stories about what people did.
This book is a case in point. Despite reading about Guadalcanal and Iwo Jima and every other ocean-based event during the war, I had never encountered any mention of what oceanographers contributed to the war effort. Come to find out that they were almost entirely women, a la Hidden Figures, is yet another of those fascinating tidbits. Not only were they instrumental in winning the war, on a personal level they fought an uphill battle against blatant sexism and never asked for anything more than to be respected for their knowledge.
These were very smart women whose scientific acumen and data-discovery helped win the war. That’s not the author saying that, that’s people like Admiral Nimitz, President Roosevelt, President Truman, and a host of US Navy captains and US Marine generals singing their praises. Talk about unsung heroes, these women are it.
Especially after the disastrous invasion of the Pacific island of Tarawa did the men running the war start taking Mary Sears and her cohort of oceanographers seriously. Tarawa was an absolute disaster from the get-go, with failures across the board. The bombs dropped and ship cannons missed their targets, leaving the entrenched Japanese soldiers able to fight, but what got 1,000 American soldiers killed and over 2,100 wounded was the fact that they didn’t fully account for the tides. The low tide stranded the Marines hundreds of yards offshore on the coral reef, where the Japanese were able to pick them off easily. After that the war planners wanted to know everything they could about tides, and the women oceanographers had those answers.
Yet another fascinating aspect of World War II.
This book is a case in point. Despite reading about Guadalcanal and Iwo Jima and every other ocean-based event during the war, I had never encountered any mention of what oceanographers contributed to the war effort. Come to find out that they were almost entirely women, a la Hidden Figures, is yet another of those fascinating tidbits. Not only were they instrumental in winning the war, on a personal level they fought an uphill battle against blatant sexism and never asked for anything more than to be respected for their knowledge.
These were very smart women whose scientific acumen and data-discovery helped win the war. That’s not the author saying that, that’s people like Admiral Nimitz, President Roosevelt, President Truman, and a host of US Navy captains and US Marine generals singing their praises. Talk about unsung heroes, these women are it.
Especially after the disastrous invasion of the Pacific island of Tarawa did the men running the war start taking Mary Sears and her cohort of oceanographers seriously. Tarawa was an absolute disaster from the get-go, with failures across the board. The bombs dropped and ship cannons missed their targets, leaving the entrenched Japanese soldiers able to fight, but what got 1,000 American soldiers killed and over 2,100 wounded was the fact that they didn’t fully account for the tides. The low tide stranded the Marines hundreds of yards offshore on the coral reef, where the Japanese were able to pick them off easily. After that the war planners wanted to know everything they could about tides, and the women oceanographers had those answers.
Yet another fascinating aspect of World War II.
October 10, 2022
WWII was such a major event in the last 100 years. We mostly learn of the big events, the big successes, the big failures, the big heroes and the big villains. However, there are so many events and people who contributed in their own little way to build up the big picture. We don't get to hear so much about these relatively unknown events or people.
This book is about a set of professionals who together made contributions to help bring the larger war to a close: oceanographers. Oceanography wasn't even a recognized science until sometime during WWII the importance of understanding tides, drifts, the temperature differences, the waves, the reefs, the winds, etc., became very vital to winning the war and thereby led to the birth of oceanography as a separate discipline -- separate from marine biology or other related fields.
In particular, there were three women whose contributions have been officially and unofficially recognized as being important to the naval battles in the Pacific. The most import of the three was Mary Sears who led the other oceanographers to make vital information available to the Navy and the Marines.
The book delves into many details of Mary Sears' life from childhood until she joined the Woods Hole Institute in Massachusetts. All of that is quite fascinating. Then of course the book gives a thorough account of how the three women came to be in DC and their contributions to the war effort.
I enjoyed this book a lot. And learnt a lot about oceanography too. But, what was disappointing was that even after the disaster of the amphibious assault on Tarawa where the importance of oceanography came home in an extremely bloody way, for the assaults on Iwo Jima and Okinawa oceanographers were largely overruled to accommodate other factors. It left me with a feeling of, "It's clear that the work that these women were doing was important; but after all that work, their role appears to be marginal to the war effort."
Unless you are a big WWII buff, you can safely skip this book.
This book is about a set of professionals who together made contributions to help bring the larger war to a close: oceanographers. Oceanography wasn't even a recognized science until sometime during WWII the importance of understanding tides, drifts, the temperature differences, the waves, the reefs, the winds, etc., became very vital to winning the war and thereby led to the birth of oceanography as a separate discipline -- separate from marine biology or other related fields.
In particular, there were three women whose contributions have been officially and unofficially recognized as being important to the naval battles in the Pacific. The most import of the three was Mary Sears who led the other oceanographers to make vital information available to the Navy and the Marines.
The book delves into many details of Mary Sears' life from childhood until she joined the Woods Hole Institute in Massachusetts. All of that is quite fascinating. Then of course the book gives a thorough account of how the three women came to be in DC and their contributions to the war effort.
I enjoyed this book a lot. And learnt a lot about oceanography too. But, what was disappointing was that even after the disaster of the amphibious assault on Tarawa where the importance of oceanography came home in an extremely bloody way, for the assaults on Iwo Jima and Okinawa oceanographers were largely overruled to accommodate other factors. It left me with a feeling of, "It's clear that the work that these women were doing was important; but after all that work, their role appears to be marginal to the war effort."
Unless you are a big WWII buff, you can safely skip this book.
January 27, 2023
"Lethal Tides" tells the story of oceanographic research and reporting during World War II. The research was conducted by a US Navy group in Washington DC. It was led by a scientist, Mary Sears, who contributed to and managed the group at a time when women were mostly relegated to minor jobs and roles. The group's reporting was essential to the war effort, particularly in the Pacific theater. Defeating Japan required difficult beach landings on a series of island across the Pacific. Each one had its own unique hazards and challenges. Sears' group was able to scour available literature to develop summary reports that naval planners could use to overcome hazards and potentially reduce loss of life and injury.
The story covers multiple themes which the author, Catherine Musemeche, must juggle. One theme is the issue of data research and management, which is not easy to understand by today's Google and Wikipedia generation. Mussemeche describes how the scientists found and assembled key information, all without an internet. A key device was something known as a "card catalog" where cards with summary information were arranged and cataloged by a manual relational database. Team members could quickly access crucial data in support of fast changing naval plans.
Another theme is the socially retro-world of 1943, when men were men and women (used to) stay home to cook. Musemeche chronicles how Sears overcame the career challenges of advancing as a capable woman in a man's world. For example, the author describes how early in her career, Sears was not able to collect her own oceanographic biological samples because a sea-faring voyage was not something that women did in those days.
The scope of the story needed to fit within the overall progression of WWII, and this is another thematic challenge for the author. Musemeche overall does a good job staying on point, while providing enough of a window on the global external events.
Musemeche's style of writing is not great, and this is one area that could have been improved. Musemeche writes with challenged clauses and awkward wording. When in doubt, she resorts to writing cliches. It is not so easy to tell an interesting tale about data management, but at times the author attributes motivations and feelings in the characters that seemed to be a bit of stretch. The manuscript would have benefited from better editing which could have caught some of these flaws.
Overall, "Lethal Tides" is meticulously researched. It tells a largely unknown story of a heroic woman who quietly contributed to the Allie's victory during WW II.
The story covers multiple themes which the author, Catherine Musemeche, must juggle. One theme is the issue of data research and management, which is not easy to understand by today's Google and Wikipedia generation. Mussemeche describes how the scientists found and assembled key information, all without an internet. A key device was something known as a "card catalog" where cards with summary information were arranged and cataloged by a manual relational database. Team members could quickly access crucial data in support of fast changing naval plans.
Another theme is the socially retro-world of 1943, when men were men and women (used to) stay home to cook. Musemeche chronicles how Sears overcame the career challenges of advancing as a capable woman in a man's world. For example, the author describes how early in her career, Sears was not able to collect her own oceanographic biological samples because a sea-faring voyage was not something that women did in those days.
The scope of the story needed to fit within the overall progression of WWII, and this is another thematic challenge for the author. Musemeche overall does a good job staying on point, while providing enough of a window on the global external events.
Musemeche's style of writing is not great, and this is one area that could have been improved. Musemeche writes with challenged clauses and awkward wording. When in doubt, she resorts to writing cliches. It is not so easy to tell an interesting tale about data management, but at times the author attributes motivations and feelings in the characters that seemed to be a bit of stretch. The manuscript would have benefited from better editing which could have caught some of these flaws.
Overall, "Lethal Tides" is meticulously researched. It tells a largely unknown story of a heroic woman who quietly contributed to the Allie's victory during WW II.
October 22, 2022
An aptly titled book about the career of pioneering oceanographer Mary Sears and the use of oceanography in WWII battle campaigns. The United States owes a HUGE debt to Sears and her mixed-gender team of marine scientists and researchers at the hydrographic lab in Washington D.C. Without their contributions to the war effort in the form of oceanographic intelligence-- information on everything from tide levels to underwater topography to the location of POW camps—, military officers would have been lacking key knowledge of enemy waters for their strategic war plans and many more lives would have been lost.
Musemeche interweaves biographical storytelling with scientific explanations of oceanography and accounts of important military campaigns that utilized oceanographic intelligence. This book could appeal to readers of various types of history. Fellow librarians out there, you in particular will enjoy reading about the important cataloging work done by one of Sears’ primary researchers, the multilingual oceanographic librarian, Mary Grier. What that woman managed to pull off by herself in a time with no computers and no internet should earn her a place in all of our library graduate school introductory courses! Why didn't I know her name until now?!
These women accomplished tremendous things in a time and place that was not very accommodating or appreciative towards them (even less so than now), and it is time that books about them appear in libraries, too!
Musemeche interweaves biographical storytelling with scientific explanations of oceanography and accounts of important military campaigns that utilized oceanographic intelligence. This book could appeal to readers of various types of history. Fellow librarians out there, you in particular will enjoy reading about the important cataloging work done by one of Sears’ primary researchers, the multilingual oceanographic librarian, Mary Grier. What that woman managed to pull off by herself in a time with no computers and no internet should earn her a place in all of our library graduate school introductory courses! Why didn't I know her name until now?!
These women accomplished tremendous things in a time and place that was not very accommodating or appreciative towards them (even less so than now), and it is time that books about them appear in libraries, too!
September 22, 2025
Lethal Tides is fantastic. I found this book at the gift shop of the Columbia River Maritime Museum and began reading it right away. I spent the first two nights reading it at the Cannery Pier Hotel, and witnessing the tides come in and out certainly accentuated the experience. Catherine Musemeche's narrative is easy and fun to read, and reveals an fascinating ancillary story of World War 2. I had no idea that the Navy's first official Oceanographer was Mary Sears, and despite a long history with the genre I had never considered how important the field was to the war effort.
Musemeche begins her story showing Mary Sears working a plankton net on December 7, 1941, immediately placing the reader in the context of the story that is about to unfold, before drifting back to describe the remarkable path that led Sears to her Ph.d. and her time at the forefront of the just emerging Woods Hole Oceanographic Institute.
At age 38, Sears had already spent an adult lifetime finding her way in a man's world only to find herself doing it again as an officer in the Navy. Combining the stories of this remarkable woman with a behind the scenes look at the logistics of war planning and the dawn of oceanography, this book's unique tale of history should find broad appeal. Highly recommended!
Musemeche begins her story showing Mary Sears working a plankton net on December 7, 1941, immediately placing the reader in the context of the story that is about to unfold, before drifting back to describe the remarkable path that led Sears to her Ph.d. and her time at the forefront of the just emerging Woods Hole Oceanographic Institute.
At age 38, Sears had already spent an adult lifetime finding her way in a man's world only to find herself doing it again as an officer in the Navy. Combining the stories of this remarkable woman with a behind the scenes look at the logistics of war planning and the dawn of oceanography, this book's unique tale of history should find broad appeal. Highly recommended!
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