26 Jun, 1944
With her trials and initial training completed USS Segundo (Lt.Cdr. J.D. Fulp, Jr.) departs New London bound for Pearl Harbour.

25 Jul, 1944
USS Segundo (Lt.Cdr. J.D. Fulp, Jr.) arrives at Pearl Harbour.

21 Aug, 1944
USS Segundo (Lt.Cdr. J.D. Fulp, Jr.) departs Pearl Harbour for her 1st war patrol. She is ordered to patrol in the Philippines.

3 Sep, 1944
USS Segundo (Lt.Cdr. J.D. Fulp, Jr.) arrives at Saipan to topp off with fuel. She departs the next day.

21 Oct, 1944
USS Segundo (Lt.Cdr. J.D. Fulp, Jr.) ends her 1st war patrol at Majuro.

16 Nov, 1944
USS Segundo (Lt.Cdr. J.D. Fulp, Jr.) departs Majuro for her 2nd war patrol. She is ordered to patrol in Luzon Strait.

6 Dec, 1944
USS Segundo (Lt.Cdr. J.D. Fulp, Jr.) torpedoes and damages the Japanese merchant cargo ships Kenjo Maru (6933 GRT), Yasukuni Maru (5794 GRT) and Shinto Maru (1215 GRT) west of Dalupiri Island, Philippines in position 18º57'N, 120º58'E.

Shinto Maru is sunk later that day by US aircraft, the Yasukuni Maru is beached and declared to total loss and the Kenjo Maru is sunk the next day by USS Trepang. (see map)

5 Jan, 1945
USS Segundo (Lt.Cdr. J.D. Fulp, Jr.) ends her 2nd war patrol at Guam.

1 Feb, 1945
USS Segundo (Lt.Cdr. J.D. Fulp, Jr.) departs Guam for her 3rd war patrol. She is ordered to patrol in the East China Sea.

11 Mar, 1945
USS Segundo (Lt.Cdr. J.D. Fulp, Jr.) torpedoes and sinks the Japanese merchant cargo ship Shori Maru (3087 GRT) off southern Korea in position 34º25'N, 127º54'E. (see map)

26 Mar, 1945
USS Segundo (Lt.Cdr. J.D. Fulp, Jr.) ends her 3rd war patrol at Pearl Harbour. In late April she departed for her 4th war patrol in the East China and Yellow Seas.

29 May, 1945
USS Segundo (Lt.Cdr. J.D. Fulp, Jr.) sinks 7 Japanese sailing vessels with gunfire in the Yellow Sea in position 37º08'N, 125º24'E. (see map)

3 Jun, 1945
USS Segundo (Lt.Cdr. J.D. Fulp, Jr.) sinks the Japanese merchant sailing vessel Anto Maru No.94 off Jinsen, Korea in position 36º41'N, 125º23'E. (see map)

7 Jun, 1945
USS Segundo (Lt.Cdr. J.D. Fulp, Jr.) sinks a small Japanese ship with gunfire in the Yellow Sea in position 37º42'N, 124º02'E. (see map)

9 Jun, 1945
USS Segundo (Lt.Cdr. J.D. Fulp, Jr.) sinks two small Japanese ships with gunfire in the Yellow Sea in position 39º08'N, 123º10'E. (see map)

11 Jun, 1945
USS Segundo (Lt.Cdr. J.D. Fulp, Jr.) torpedoes amd sinks the Japanese merchant cargo ship Fukui Maru No.2 (1591 GRT) in the Yellow Sea off the Shantung peninsula in position 37º11'N, 123º23'E.

After this sinking Suguno pointed her bow back home towards Midway. (see map)

10 Aug, 1945
USS Segundo (Lt.Cdr. S.L. Johnson) departs Midway for her 5th war patrol. She is ordered to patrol in the Sea of Okhotsk.

29 Aug, 1945
USS Segundo (Lt.Cdr. S.L. Johnson) encounters the Japanese submarine I-401 off the northeast coast of Honshu, and after negotiations placed a prize crew on board the Japanese submarine. Both submarines then proceeded to Tokyo Bay.

31 Aug, 1945
USS Segundo (Lt.Cdr. S.L. Johnson) enters Tokyo Bay.