USS Hammerhead (SS-364), a Gato-class submarine, was the first ship of the United States Navy to be named for the hammerhead shark, a shark found in warm seas with a flattened anterior forward of the gill slits, presenting a hammer-like silhouette when viewed from above. Construction and commissioning Hammerhead initially was ordered as a unit of the Balao class, but her builder, the Manitowoc Shipbuilding Company, did not receive the drawings for the Balao class from the Electric Boat Company in time to build Hammerhead or the submarines , , and to the new design, so they were built as Gato-class submarines. Thus, in some references, these four submarines are listed as units of the Balao-class. Hammerhead was launched on 24 October 1943 by the Manitowoc Shipbuilding Compnay at Manitowoc, Wisconsin, sponsored by Mrs. R. W Berry, and commissioned on 1 March 1944. Operational history After a month's training in Lake Michigan, Hammerhead was placed in a floating drydock and towed down the Mississippi River to New Orleans, Louisiana, where she arrived on 8 April 1944. She subsequently proceeded to Balboa, Panama Canal Zone, for further training, and thence to Pearl Harbor, Hawaii. First patrol, June – August 1944 The submarine departed Pearl Harbor on her first war patrol 6 June 1944 in company with and . Cruising the seas south of Formosa, her first engagement came 9 June when she sank a sampan with gunfire. She then encountered a coastal oiler 29 June and closed for the attack, but the torpedoes failed to strike home and a surprise aerial attack forced the sub down. At the Next day, Hammerhead damaged several ships of a convoy. She made port at Fremantle, Australia 17 August 1944. Second patrol, September – November 1944 Hammerhead'''s second war patrol was conducted in the Java and South China Seas. She departed Fremantle 9 September and made her first attack the night of 1 October, when a convoy consisting of four cargo ships, one oiler, and three escorts was detected off Borneo. Hammerhead fired 10 torpedoes, scored a total of 6 hits, and sent 3 of the cargo ships to the bottom (Hiyori Maru, Higane Maru, Kokusei Maru). The morning of 20 October the submarine found still another six ship convoy, and after evading one of the escorts delivered a six-torpedo attack. Two more cargo ships fell victim to Hammerheads marksmanship. The submarine returned from this