A native of Mobile, Alabama, he saw action as a sergeant major in the Seven Days Battles, and later became a second lieutenant in the Confederate States Marine Corps.

During the Battle of Frayser's Farm, June 30, 1862, part of the Seven Day's campaign, he was blinded temporarily by a shell exploding inches from his face.

In March, it is reported that Secretary Mallory offered him a commission in the Confederate Marine Corps, but Rapier did not initially accept it.

[1] On August 1, he was ordered to report to Secretary Mallory, where he was then assigned to the Marine Camp at Drewry's Bluff, James River, Virginia, as part of Company A.

[1][2] He served there briefly until he was ordered on December 22, 1863, to report to Admiral Franklin Buchanan, commander of the Mobile Squadron.

On August 3, 1864, Rapier and several fellow marines were ordered to reinforce Fort Gaines on Dauphin Island, Mobile Bay, Alabama, during which time he was made Major W. R. Browne's adjutant.

[2] He later escaped from prison in New Orleans on October 13, 1864, by making his way through the swamps and bayous until he reached Mobile on November 10.

[1] In December 1894, President Grover Cleveland appointed him Postmaster of Mobile, which position he held until March 1897.