The battle of Shiloh on April 6-7 1862 was the biggest battle of the Civil War up to that date; the gallant stand of the then-unknown Union General Ulysses S. Grant created a new national hero and was the turning point in the career of the Civil War's eventual victor.
This description of the campaign which culminated in the Battle of Shiloh, is a little bit of a struggle to wade through, but is full of charts, maps, and side-bar entrees on various topics.