George McClellan was a prominent American military officer and politician 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 led Union forces in several key battles. Despite his organizational skills and ability to train troops, McClellan faced criticism for his cautious approach in battle. He was eventually removed from command in 1862 after the Battle of Antietam, and later ran for president in 1864 against Abraham Lincoln.