Born in Granville, Washington County, New York, Tanner completed preparatory studies.

He studied law, and was admitted to the bar in 1854 and commenced practice in Whitehall, New York.

During the Civil War, Tanner entered the Union Army in 1862 as a captain in command of Company C, 123rd New York Volunteer Infantry Regiment.

He was promoted through the ranks, and was the regiment's lieutenant colonel and second in command at the close of the war.

This article incorporates public domain material from the Biographical Directory of the United States Congress