, a Gato-class submarine, was the first submarine and second ship of the United States Navy to be named for the cero. Construction and commissioning Cero'''s keel was laid down on 24 August 1942 by Electric Boat Company, Groton, Connecticut. She was launched 4 April 1943, sponsored by Mrs. Katherine J. Barbey — the wife of Rear Admiral Daniel E. Barbey, Commanding officer of the Amphibious Force, Southwest Pacific Force at the time — and commissioned 4 July 1943. First War PatrolCero cleared New London 17 August 1943 for Pacific waters, and on 26 September sailed from Pearl Harbor, bound for the East China and Yellow Seas on her first war patrol. This patrol was also the first American wolfpack, comprising Cero, , and , commanded from Cero by Captain "Swede" Momsen. At dawn on 12 October, Cero made her first attack, on a convoy of three freighters escorted by two destroyers; one of the merchantmen was heavily damaged. During this patrol, she damaged two other freighters, and a small patrol boat which she engaged on the surface. Second, Third, and Fourth War Patrols After refitting at Midway from 16 November to 13 December 1943, Cero, Edward Dissette commanding, made an unproductive second war patrol along the Truk-New Ireland route, then put into Milne Bay, New Guinea, from 12 January to 4 February 1944. Returning to the Truk-New Ireland shipping lanes, she attacked a freighter (later sunk by one of her sister submarines) and inflicted damage on another merchantman. She put into Brisbane, Australia, 2 March, and sailed 3 April on her fourth war patrol, off the Palau Islands. On 11 April 1944, a United States Army Air Forces B-24 Liberator bomber mistakenly strafed and bombed Cero as she submerged in the western Pacific Ocean about east-northeast of Biak Island. Cero suffered no damage or casualties. Her most successful day to date came on 23 May 1944, when she attacked two freighters and a tanker, sinking one cargo ship, and damaging the tanker. Fifth and Sixth War PatrolsCero was refitted at Seeadler Harbor, Manus, from 2 to 26 June 1944, then put to sea for the dangerous waters off Mindanao, where on 5 August, she sent another tanker to the bottom; fifteen days later she finished her fifth patrol at Brisbane. On 19 September 1944, Cero cleared Darwin, Australia, for the Mindanao and Sulu Seas for her sixth patrol. She