17 Aug, 1943
With her trials and training completed USS Cero (Lt.Cdr. D.C. White) departs New London for Pearl Harbour.

26 Sep, 1943
USS Cero (Lt.Cdr. D.C. White) departs Pearl Harbour for her 1st war patrol. She was ordered to patrol in the East China / Yellow Sea.

16 Nov, 1943
USS Cero (Lt.Cdr. D.C. White) ends her 1st war patrol at Midway.

13 Dec, 1943
USS Cero (Lt.Cdr. E.F. Dissette) departs Midway for her 2nd war patrol. She is ordered to patrol in the Caroline Islands area.

12 Jan, 1944
USS Cero (Lt.Cdr. E.F. Dissette) ends her 2nd war patrol Milne Bay, New Guinea.

4 Feb, 1944
USS Cero (Lt.Cdr. E.F. Dissette) departs Milne Bay for her 3rd war patrol. Once again she is ordered to patrol in the Caroline islands area.

17 Feb, 1944
USS Cero (Lt.Cdr. E.F. Dissette) torpedoes and sinks the Japanese troop transport Jozan Maru (1086 GRT) between Truk and New Ireland in position 00º53'N, 146º26'E. (see map)

21 Feb, 1944
USS Cero (Lt.Cdr. E.F. Dissette) torpedoes and damages the Japanese army cargo ship Hasshu Maru (2655 GRT) north of New Guinea in position 00º10'S, 139º45'E. (see map)

2 Mar, 1944
USS Cero (Lt.Cdr. E.F. Dissette) ends her 3rd war patrol at Brisbane, Australia.

3 Apr, 1944
USS Cero (Lt.Cdr. E.F. Dissette) departs Brisbane for her 4th war patrol. She is ordered to patrol off the Palau Islands.

23 May, 1944
USS Cero (Lt.Cdr. E.F. Dissette) torpedoes and sinks the Japanese army cargo ship Taijun Maru (2825 GRT) and together with USS Ray torpedoes and damages the Japanese army tanker Kenwa Maru (6384 GRT) north-east of Morotai in position 02º42'N, 128º08'E. (see map)

2 Jun, 1944
USS Cero (Lt.Cdr. E.F. Dissette) ended her 4th war patrol at Manus.

26 Jun, 1944
USS Cero (Lt.Cdr. E.F. Dissette) departs Manus for her 5th war patrol. She is ordered to patrol in the Philippines.

5 Aug, 1944
USS Cero (Lt.Cdr. E.F. Dissette) torpedoes and sinks fleet oiler Tsurumi (10450 GRT) off Davao Gulf, Philippines in position 05º53'N, 125º41'E. (see map)

20 Aug, 1944
USS Cero (Lt.Cdr. E.F. Dissette) ends her 5th war patrol at Brisbane.

19 Sep, 1944
USS Cero (Lt.Cdr. E.F. Dissette) departs Darwin, Australia for her 6th war patrol. She is ordered to patrol off Mindanao, Philippines.

27 Oct, 1944
USS Cero (Lt.Cdr. E.F. Dissette) drives the Japanese guardboat Kyoei Maru No.3 (38 GRT) ashore on Luzon in position 17º00'N, 119º00'E. (see map)

3 Nov, 1944
USS Cero (Lt.Cdr. E.F. Dissette) lands men and supplies on east coast of Luzon.

24 Nov, 1944
USS Cero (Lt.Cdr. E.F. Dissette) ends her 6th war patrol at Pearl Harbour. She was ordered to the Mare Island Navy yard for an major overhaul.

31 Mar, 1945
With her overhaul completed USS Cero (Lt.Cdr. R. Berthrong) departs Pearl Harbour for her 7th war patrol. She was ordered to patrol in Japanese home waters off Honshu and Hokkaido.

19 Apr, 1945
USS Cero (Lt.Cdr. R. Berthrong) sinks the Japanese guardboat Isuzu Maru no.3 (74 GRT) with gunfire south of Honshu, Japan in position 30º42'N, 136º42'E. (see map)

22 Apr, 1945
USS Cero (Lt.Cdr. R. Berthrong) sinks the Japanese guardboat Aji Maru (107 GRT) west of Tori Jima in position 31º38'N, 139º00'E, and damages guardboat Takamiya Maru No.9 in position 30º04'N, 136º43'E. (see map)

29 Apr, 1945
USS Cero (Lt.Cdr. R. Berthrong) torpedoes and sinks the Japanese merchant cargo ship Taishu Maru (6925 GRT) off Kamaishi, Japan in position 39º15'N, 141º58'E. (see map)

4 May, 1945
USS Cero (Lt.Cdr. R. Berthrong) torpedoes and sinks the Japanese merchant cargo ship Shinpen Maru (884 GRT) off Yamada Bay in position 39º28'N, 142º04'E. (see map)

13 May, 1945
USS Cero (Lt.Cdr. R. Berthrong) torpedoes and sinks the Japanese merchant cargo ship Shinnan Maru (1025 GRT) off Todozaki, Honshu, Japan in position 39º06'N, 141º57'E. (see map)

20 May, 1945
USS Cero (Lt.Cdr. R. Berthrong) torpedoes and sinks the Japanese merchant whaler Seki Maru No.5 (377 GRT) east-south-east of Kinkazan, Japan in position 38º06'N, 142º24'E. (see map)

27 May, 1945
USS Cero (Lt.Cdr. R. Berthrong) ends her 7th war patrol at Guam.

27 Jun, 1945
USS Cero (Lt.Cdr. R. Berthrong) departs Guam for her 8th war patrol. She is ordered to perform lifeguard and picket duty off Honshu, Japan.

15 Jul, 1945
USS Cero (Lt.Cdr. R. Berthrong) rescued three survivors of a downed bomber and bombarded the Japanese lighthouse and radio station at Shiriya Saki, Honshu.

18 Jul, 1945
USS Cero (Lt.Cdr. R. Berthrong) is damaged by a bomb from a Japanese aircraft off the Kuril Islands in positioon 45º14'N, 148º41'E. Due to the damages she is forced to terminate her patrol. (see map)

30 Jul, 1945
USS Cero (Lt.Cdr. R. Berthrong) ends her 8th war patrol at Pearl Harbour.