Ernest Hellensmith was born on June 4, 1920, in Moberly, Missouri. He enlisted in the U.S. Navy on April 10, 1941, and completed basic training and Electrician School at NTS San Diego, California, in October 1941. His first assignment was aboard the submarine tender USS Fulton (AS-11) from November 1941 to June 1942, and then spent one day aboard the submarine USS Gato (SS-212) before joining the crew of the submarine USS Grunion (SS-216) on June 29, 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 a member of the crew of the U.S.S. GRUNION which destroyed three enemy destroyers while engaged in a war patrol in enemy controlled waters. Despite severe 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 a member of the crew of the GRUNION, your performance of duty was an important and material contribution to the prosecution of this war.