William Hawley was born on August 19, 1824 in Lockport, New York. He served in the Mexican War, going on to become a Madison, Wisconsin furniture dealer and manufacturer.

On April 24, 1861 he became Captain of Company K of the 3rd Wisconsin Infantry Regiment. He was wounded at the Battle of Cedar Mountain on August 9, 1862, and again at Chancellorsville on May 1, 1863. By Gettysburg he had advanced to colonel, and commanded the regiment. He was wounded for a third time at New Hope Church on May 25, 1864. Hawley mustered out on July 18, 1865.

He died on July 15, 1873 in Buffalo, New York.