Having enlisted in the Union Army's Second Iowa Infantry during the Civil War, Lieutenant Colonel Chipman fought courageously in battle and was nearly mortally wounded and carried off the battlefield, leading his commanders to report him as dead at the Battle of Fort Donelson. Chipman did, in fact, survive and, upon recovery, was promoted to the rank of colonel in 1862. Chipman and fellow Ohioan Ulysses S. Grant fought together in the Battle of Fort Donelson, which became Grant's first major victory. Chipman was later appointed as a member of General Henry W. Halleck's and then Samuel R. Curtis's staff. He later became a member of the Judge Advocate General's staff.