Theodore Ayrault Dodge (1842-1909) was the nineteenth century’s greatest military historian and the author of biographies of Hannibal, Alexander the Great, Julius Caesar, Gustavus Adolphus, and Napoleon. In 1862, he arrived on the Virginia Peninsula as a company officer in the 101st New York, a regiment reinforcing George B. McClellan’s campaign against Richmond. Here is the war as seen from the company-officer perspective, recorded by a young man of superior intellect who would become a leading historian of the Civil War generation. Although only some thirteen months of the war are detailed here, from the Peninsula through Gettysburg, where he lost a leg, they were critical months for the Union cause.