A native of Cameron, New York, William Averell graduated from the military academy at West Point in 1855. Wounded in action against the Indians in 1859, he was placed on the disabled list until the outbreak of the Civil War.
During the war, Averell saw action at the First Battle of Bull Run, the Peninuslar Campaign, Antietam, Fredericksburg, Chancellorsville, and the Shenandoah Valley campaign, rising to the rank of brigadier general of volunteers. At the end of the war, he was honored with a brevet to major general, U.S. Army.
Averell resigned from the army when peace came and accepted an appointment as U.S. consul general to British North America (1866-1869. In later life his skill as an inventor of practical devices provided him with a handsome income. General Averell died and was buried at Bath, New York.