George B. McClellan

George B. McClellan (1826–1885) was a Union major general during the American Civil War who organized and commanded the Army of the Potomac. He is best known for his role in building and training the Union's principal field army in the Eastern Theater, his cautious conduct during the Peninsula Campaign and the Battle of Antietam, and his subsequent challenge to Abraham Lincoln as the Democratic presidential nominee in 1864. After the war he served as governor of New Jersey from 1878 to 1881.