One night in February 1943, this airman was the navigator of an aircraft detailed for a mine-laying mission off the Frisian Islands. In the course of the operation an enemy fighter engaged the aircraft raking its fuselage with machine-gun fire. The flight engineer and the rear gunner were killed while Sergeant Mellin was hit in the leg by a bullet which caused a compound fracture to the fibia and tibea bones. Despite the severity of his injuries, this airman assumed the duties of the flight engineer, while other members of the crew were quelling flames which had broken out in the bomber. He afterwards returned to his navigational duties, proving of great assistance to his pilot who flew the damaged aircraft to an airfield in this country. Although he had lost much blood and was in intense pain, it was only when the aircraft was about to be landed that Sergeant Mellin would consent to leave his post. His exemplary conduct and great fortitude were worthy of the highest praise.