William Speer Kirkwood was born on July 4, 1835 in Fairview, Allegheny County, Pennsylvania. He lived in Pittsburgh, where he worked as a farmer and ferryman.

On August 26, 1861 Kirkwood became Captain of Company B of the 63rd Pennsylvania Volunteer Infantry.

In March of 1862 the regiment was moved to the Peninsula as part of Heintzleman’s Third Corps, fighting in the Battle of Fair Oaks. It then joined Pope’s Army of Virginia near Manassas.

Kirkwood was wounded in the right leg at the Battle of Groveton on August 29, 1862. He returned to the regiment and was promoted to lieutenant colonel on November 6. On April 18, 1863 he was promoted to colonel.

Kirkwood was mortally wounded leading his regiment at the Battle of Chancellorsville on May 3, 1863, shot in the leg and chest. He died on June 25 at Alexandria, Virgina, and is buried in Allegheny Cemetery in Pittsburg.