George Brinton McClellan was an American soldier, Civil War Union general, civil engineer, railroad executive, and politician who served as the 24th Governor of New Jersey. A graduate of West Point, McClellan served with distinction during the Mexican–American War, and later left the Army to serve as an executive and engineer on railroads until the outbreak of the American Civil War. Early in the conflict, McClellan was appointed to the rank of major general and played an important role in raising a well-trained and disciplined army, which would become the Army of the Potomac in the Eastern Theater; he served a brief period as Commanding General of the United States Army of the Union Army.
McClellan organized and led the Union army in the Peninsula Campaign in southeastern Virginia from March through July 1862. It was the first large-scale offensive in the Eastern Theater. Making an amphibious clockwise turning movement around the Confederate Army in northern Virginia, McClellan's forces turned west to move up the Virginia Peninsula, between the James River and York River, landing from Chesapeake Bay, with the Confederate capital, Richmond, as their objective.