McClellan, George Brinton. American general. Born in 1826. Distinguished himself in the Mexican War, and drew up a report on the organization of European armies after a visit to the Crimea. During the Civil War, commanded the army of the Potomac, but after indecisive engagements, was superseded in 1862. In 1864, as a Democrat, he was the unsuccessful opponent of Lincoln for the presidency. In 1877, he was elected governor of New Jersey. Died 1885.