18 May, 1944
With her trials and initial training completed USS Piranha (Lt.Cdr. H.E. Ruble) arrives at Pearl Harbour.

14 Jun, 1944
USS Piranha (Lt.Cdr. H.E. Ruble) departs Pearl Harbour for her 1st war patrol. She is ordered to patrol off Luzon Strait.

12 Jul, 1944
USS Piranha (Lt.Cdr. H.E. Ruble) torpedoes and sinks the Japanese tanker Nichiran Maru (6503 GRT) off the north-east coast of Luzon, Philippines in position 18º50'N, 122º40'E. (see map)

16 Jul, 1944
USS Piranha (Lt.Cdr. H.E. Ruble) torpedoes and sinks the Japanese troop transport Seattle Maru (5773 GRT) in Luzon Strait in position 19º17'N, 120º15'E. (see map)

8 Aug, 1944
USS Piranha (Lt.Cdr. H.E. Ruble) ends her 1st war patrol at Majuro.

30 Aug, 1944
USS Piranha (Lt.Cdr. H.E. Ruble) departs Majuro for her 2nd war patrol. She is ordered to patrol off the Palau's to support the landings at Peleliu. Later she was ordered to patrol north of the Philippines.

23 Oct, 1944
USS Piranha (Lt.Cdr. H.E. Ruble) ends her 2nd war patrol at Pearl Harbour.

13 Nov, 1944
USS Piranha (Lt.Cdr. H.E. Ruble) departs Pearl Harbour for her 3rd war patrol. She is ordered to patrol in the East China Sea.

8 Jan, 1945
USS Piranha (Lt.Cdr. H.E. Ruble) torpedoes and damages the Japanese auxiliary netlayer Shinto Maru No.2 (540 GRT) off the Ryukyu Islands in position 29º55'N, 130º05'E. (see map)

13 Jan, 1945
USS Piranha (Lt.Cdr. H.E. Ruble) ends her 3rd war patrol at Guam.

11 Feb, 1945
USS Piranha (Lt.Cdr. H.E. Ruble) departs Guam for her 4th war patrol. She is ordered to patrol off Formosa.

27 Feb, 1945
USS Piranha (Lt.Cdr. H.E. Ruble) sinks a Japanese sampam with gunfire off the south coast of Formosa in position 22º15'N, 120º17'E. (see map)

21 Apr, 1945
USS Piranha (Lt.Cdr. H.E. Ruble) ends her 4th war patrol at Midway.

17 May, 1945
USS Piranha (Cdr. D.G. Irvine) departs Midway for her 5th war patrol. She is ordered to patrol off Honshu in Japanese home waters.

16 Jun, 1945
USS Piranha (Cdr. D.G. Irvine) torpedoes and sinks the Japanese merchant cargo ship Eiso Maru (6890 GRT) off the northern coast of Honshu, Japan in position 41º57'N, 140º56'E.

17 Jun, 1945
USS Piranha (Cdr. D.G. Irvine) sinks a small Japanese vessel with gunfire off the northern coast of Honshu, Japan in position 42º07'N, 141º36'E.

21 Jun, 1945
USS Piranha (Cdr. D.G. Irvine) damages the Japanese merchant cargo ship Shirogane Maru (122 GRT) with gunfire off the east coast of Honshu, Japan in position 39º28'N, 142º10'E. (see map)

22 Jun, 1945
USS Piranha (Cdr. D.G. Irvine) torpedoes and damages the Japanese corvette Kaibokan No.196 (740 tons) off the east coast of Honshu, Japan in position 39º32'N, 142º11'E. (see map)

23 Jun, 1945
USS Piranha (Cdr. D.G. Irvine) sinks two small Japanese vessels with gunfire off the east coast of Honshu, Japan at positions 39º09'N, 142º10'E and 39º01'N, 142º01'E. (see map)

10 Jul, 1945
USS Piranha (Cdr. D.G. Irvine) ends her 5th war patrol at Pearl Harbour.

14 Aug, 1945
USS Piranha (Cdr. D.G. Irvine) departs Pearl Harbour for her 6th war patrol but after only half a day at sea she was ordered back as hostilities ended.