George Brinton McClellan (December 3, 1826 – October 29, 1885) was a major general during the American Civil War. He organized the famous Army of the Potomac and served briefly (November 1861 to March 1862) as the general-in-chief of the Union Army. Early in the war, McClellan played an important role in raising a well-trained and organized army for the Union. Although McClellan was meticulous in his planning and preparations, these characteristics may have hampered his ability to challenge aggressive opponents in a fast-moving battlefield environment. He chronically overestimated the strength of enemy units and was reluctant to apply principles of mass, frequently leaving large portions of his army unengaged at decisive points.
McClellan's Peninsula Campaign in 1862 ended in failure, with retreats from attacks by General Robert E. Lee's smaller Army of Northern Virginia and an unfulfilled plan to seize the Confederate capital of Richmond. His performance at the bloody Battle of Antietam blunted Lee's invasion of Maryland, but allowed Lee to eke out a precarious tactical draw and avoid destruction, despite being outnumbered. As a result, McClellan's leadership skills during battles were questioned by U.S. President Abraham Lincoln, who eventually removed him from command, first as general-in-chief, then from the Army of the Potomac. Lincoln offered this famous evaluation of McClellan: "If he can't fight himself, he excels in making others ready to fight." Indeed, McClellan was the most popular of that army's commanders with its soldiers, who felt that he had their morale and well-being as paramount concerns.
General McClellan also failed to maintain the trust of Lincoln, and proved to be frustratingly derisive of, and insubordinate to, his commander-in-chief. After he was relieved of command, McClellan became the unsuccessful Democratic nominee opposing Lincoln in the 1864 presidential election. His party had an anti-war platform, promising to end the war and negotiate with the Confederacy, which McClellan was forced to repudiate, damaging the effectiveness of his campaign. He served as the 24th Governor of New Jersey from 1878 to 1881. He eventually became a writer, defending his actions during the Peninsula Campaign and the Civil War.