"A Man Called Intrepid" is partly an account of Canadian-born spymaster William Stephenson's central role in the development of the British-American intelligence system during WW2; and partly a revelation of the absolutely critical role that intelligence services (e.g. code-breaking, espionage, and sabotage) played in the defeat of the Axis powers in WW2. I use the term "revelation" because at the time of it's publication in 1976, the secrets of Bletchley Park (the British code-breaking center disguised as a radio factory) and ULTRA (code name for British intelligence information) had only recently been declassified.
WW2 is often discussed as a conflict decided by sheer military might. While it is true that the combined power of the Russian, British and American armies was essential to Allied victory, this book proves that the war would have been lost before the Americans formally intervened if it were not for the actions of Stephenson's clandestine intelligence agency operating in Bletchley, Canada, and the US. A prominent example of this is the role that ULTRA played in anticipating German strategy during the Battle of Britain. More intriguing, though, are the lesser-known examples of Stephenson's network's direct influence on Allied victories and overall strategy throughout the war - e.g. the coordination of Yugoslav resistance to the Nazis under "Tito" (which fatally delayed the German invasion of Russia); the disruption of the Norsk Hydro plant in Norway to prevent German nuclear armament; and the "disastrous" raid on Dieppe intended to confuse the Germans about the planned location of the D-Day invasion.
Moreover, the author's examination of heretofore concealed intelligence that influenced Allied decision making adds valuable perspective to the debate over certain morally questionable acts of violence carried out by the British and the Americans during the the war, including the planned assault on a Gestapo center in Copenhagen that resulted in predictable civilian deaths. The author provides detailed context - unknown to the public for years - for some of the wartime decisions that likely tortured Stephenson, Churchill and others involved in the highest levels of intelligence gathering and war planning. However, at one point the author unnecessarily tips the scale in favor of his subject by quoting the family member of a civilian killed in an Allied bombing raid. The anonymous family member forgives the planners of the raid and retrospectively acknowledges the strategic value of the attack.
Even those uninspired by military history will find appeal in the accounts of tremendous individual cunning and sacrifice shown by the members of Stephenson's vast spy network. The author highlights in thrilling detail the exploits of regular men and women transformed into spies and saboteurs, such as the infamous code name CYNTHIA, an American socialite who engaged with married foreign diplomats to among other objectives pilfer French naval codes and obtain other details of the Vichy French strategy. A quick internet search reveals that some of these stories are refuted or dismissed as exaggeration, but to the extent that the author's descriptions are regarded as truthful they evince the extremely personal nature of warfare during WW2, as well as the extent to which large-scale military operations depended on the secretive actions of civilians turned spies.
I would characterize this book as essential reading for military historians. It is likely the first, and probably the most comprehensive, account of William Stephenson's role in building the vast and indispensable intelligence network that kept Great Britain in the fight long enough to compel American intervention, and which eventually formed the backbone of intelligence gathering and strategic operations on the Allied side throughout WW2. More importantly, though, the book conveys, and supports with intricate detail, the reality that the most massive and consequential conflict of our time was decided by the ingenuity of code-breakers, civilian spies, and unassuming men like William Stephenson, who to a great extent remain absent from the history books.