He quit high school at seventeen to enlist in the U.S. Navy on August 16, 1947, from Houston, Texas.

He enlisted as an Apprentice Seaman, and after his recruit training, he attended Hospital Corps School, San Diego, California.

[1] Kilmer was assigned to the hospital ship USS Repose when the Korean War began in June 1950.

In April 1952, after running afoul of a superior, Kilmer chose to volunteer to serve as a corpsman with a Fleet Marine Force (FMF) unit.

[4][5] On 16 October 2019, U.S. Secretary of the Navy Richard V. Spencer announced that it will name a new Arleigh Burke-class guided missile destroyer in his honor – the USS John E. Kilmer (DDG-134).