Abner Doubleday (1819-1893) had one of the lengthiest Civil War resumes and an influence that made him worthy of national recognition. Doubleday is credited with firing the first shot in defense of Fort Sumter, the opening fight of the war, and he played a pivotal role on the first day of the Battle of Gettysburg, taking command of the I Corps early on the morning of July 1, 1863 after General John Reynolds was killed. Doubleday also led a division at South Mountain and then at Antietam, where he was injured during deadly fighting in the Cornfield and the West Woods. One colonel described him as a "gallant officer ... remarkably cool and at the very front of battle," and his personal character was so admired among the rank-and-file that one of his men humorously asserted, "He is deficient considerably in the requisites of a commander. He does not drink whiskey...stays with his command and seems anxious to do his duty and fight Rebels....He also allows his wife to stay with him when he ought to keep a mistress." Despite his Civil War service, few people remember Abner Doubleday for his military career today, and it has basically been relegated to the status of historical footnote. Instead, Doubleday has become the inadvertent beneficiary of the myth that he invented baseball, and he is almost universally remembered for that claim. In conjunction, the widespread belief that Doubleday invented baseball resulted in his hometown of Cooperstown, New York becoming home of Major League Baseball's Hall of Fame. This is all in spite of the fact that Doubleday never claimed to have invented the game much less said anything of note about it, which should come as no surprise since baseball was so commonplace by then that it was a popular game played in army camps among Civil War soldiers on both sides. In this work, he discusses the pivotal battles of Chancellorsville and Gettysburg, fought in May 1863 and July 1863 respectively.