George Stoneman was born in New York in 1822. He joined the US Army and served in the Mexican War. On the outbreak of the American Civil War he joined the Union Army and was commissioned major of the 1st US Cavalry.

In August, 1862, he was promoted to brigadier general of the 4th US Cavalry. In October, 1861, Stoneman joined the Army of the Potomac and during the Peninsular campaign he commanded the cavalry division in its attempt to capture Richmond (June, 1863).

Promoted to the rank of major general Stoneman fought at Fredericksburg (December, 1862) and Chancellorsville (May, 1863). He also served under William T. Sherman during the Atlanta Campaign.

After the war, Stoneman, a member of the Democratic Party, served in several official posts. George Stoneman died in Los Angeles in 1894.