George B. McClellan was a prominent American military officer during the American Civil War. Born on December 3, 1826, he graduated from the United States Military Academy at West Point and served in the Mexican-American War. McClellan is best known for his role as the commander of the Army of the Potomac, where he organized and trained troops. Despite his organizational skills, McClellan faced criticism for his cautious approach in battle. He led the Union forces during key campaigns, including the Peninsula Campaign and the Battle of Antietam. Ultimately, he was removed from command in 1862, but he later served as the Governor of New Jersey.