John Kelvin Koelsch joined the U.S. Naval Reserve as an aviation cadet on September 14, 1942, and was commissioned as an ensign on October 23, 1944, after completing flight training. During the next few years, he served at Naval Air Stations at Fort Lauderdale, Florida, and Norfolk, Virginia, and subsequently flew with Composite Squadron 15 and Torpedo Squadrons 97 and 18. He became an accomplished torpedo bomber pilot, and was promoted to lieutenant (junior grade) on August 1, 1946.

After the outbreak of the Korean War, he joined Helicopter Squadron 1 (HU-1) at Miramar, California, in August 1950. As Officer in Charge of a helicopter detachment, he joined USS Princeton in October for pilot rescue duty off the eastern coast of Korea. He served in Princeton until June 1951, when he joined Helicopter Squadron 2 (HU-2) for pilot rescue duty off Wonsan, Korea, then under naval blockade. He provided lifeguard duty for pilots who were downed either in coastal waters or over enemy-held territory. On June 22, he rescued a naval aviator from the waters of Wonsan Harbor, southeast of Yo Do Island.

-Namesake for the USS Koelsch (DE-1049/FF-1049)

Koelsch, John Kelvin, LTJG