William Kornahrens was born on February 12, 1916, in Brooklyn, New York. He entered the U.S. Naval Academy on June 12, 1934, and was commissioned an Ensign in the U.S. Navy on June 1, 1939. Ens Kornahrens next served aboard the light cruiser USS Trenton (CL-11) from June 1939 to February 1941, followed by Submarine School at Submarine Base New London, Connecticut, from April to June 1941. He then served aboard the submarine USS O-6 (SS-67) from July 1941 to February 1942. Lt Kornahrens joined the crew of the USS Grunion (SS-216) during her fitting out in February 1942, and remained aboard through her commissioning in April 1942. He was killed in action during a confrontation with the armed Japanese freighter Kano Maru on July 30, 1942. On August 22, 2007, a search team organized by the three sons of CDR Mannert Abele (the Captain of the Grunion when she was sunk) used a remotely operated vehicle to find a sunken vessel 3,000 feet down in the Bering Sea north of Kiska Island at the tip of the Aleutian Islands. On October 1, 2008, the U.S. Navy announced that the sunken vessel is the World War II submarine USS Grunion (SS-216).

His Navy Commendation Medal Citation reads:

For meritorious conduct as Gunnery Officer of the U.S.S. GRUNION which destroyed three enemy destroyers while engaged in a war patrol in enemy controlled waters. Despite sever and persistent anti-submarine measures resulting from these three successful attacks, the GRUNION was brought safely through the counter attacks and continued an aggressive war patrol. As Gunnery Officer of the GRUNION, your performance of duty was an important and material contribution to the prosecution of this war.