McClellan (1826-1885) graduated second in his class from West Point and served in the Mexican War. He resigned from the Army in 1857 to work as an engineer and administrator for the railroad and became president of the Ohio and Mississippi Railroad in 1860.

At the beginning of the Civil War, he was commissioned major general of the Union forces in Ohio and lost the First Battle of Bull Run. He later became the commander of the Army of the Potomac and, in 1861, replaced Winfield Scott as general in chief of the Army. Lincoln considered him too hesitant and not aggressive enough. He fought Robert E. Lee to a standstill at Antietam (1862) but was criticized for not pursuing the Confederate forces and was relieved of command.

He was the Democratic candidate for the presidency in 1864 but was defeated by Lincoln.

He went on to serve as governor of New Jersey from 1878-1881.