William Dunlap was born around 1843 in Ohio. By 1860, he was living in Marion, Indiana, and working on the farm of Charles Robbins. He enlisted in the Union army on September 24, 1861, and mustered in as a private in Company A of the 30th Indiana Infantry later that day. The regiment took part in the Battle of Shiloh, the siege of Corinth, the Battle of Stones River, the Battle of Chickamauga, and the Atlanta campaign. He was captured by Confederate forces and imprisoned in Andersonville. He died there on September 24, 1864.