The Sargo was the first vessel equipped with a new lead-acid battery designed by the Bureau of Steam Engineering (BuEng) to resist battle damage, based on a suggestion by her commissioning commanding officer, Lieutenant E. E.

Leaking sulfuric acid would be capable of corroding steel, burning the skin of crew members it came into contact with, and if mixed with any seawater in the bilges it would generate poisonous chlorine gas.

After shakedown along the eastern seaboard of South America, Sargo departed Portsmouth, New Hampshire, in July 1939 for duty with the Pacific Fleet.

Off the major Japanese base at Cam Ranh Bay, ULTRA intercepts directed her to three cruisers on 14 December, but the Sargo was unable to gain position to attack when they appeared as scheduled.

[9] Temporarily losing depth control, she broached, and the target turned away; Sargo fired two stern tubes at 1,800 yards (1,600 m), with no more success.

[10] A few days afterward, a big, slow tanker gave Sargo another opportunity, and again, the approach was meticulous, firing one torpedo at a close 1,200 yards (1,100 m).

On 4 March 1942 she was one day out of Fremantle, Western Australia, when a Royal Australian Air Force Lockheed Hudson patrol bomber mistook her for a Japanese submarine and attacked her at 13:38 while she was on the surface at 30°27′S 113°37′E / 30.450°S 113.617°E / -30.450; 113.617.

[17] During March, amid the panic over potential Japanese invasion of Australia, Sargo (now commanded by Richard V. Gregory, Class of 1932)[18] was detailed to guard Darwin's approaches.

When these did not sink the target, three more were fired; all missed, including one circular, which exploded off her stern,[19] presaging another deadly failing of the Mark 14.

[20] On 29 November, she departed Brisbane and conducted her sixth patrol (now commanded by Edward S. Carmick, Class of 1930)[21] en route to Hawaii.

She arrived at Pearl Harbor on 21 January 1943 and proceeded to San Francisco Bay for a three-month overhaul in the Mare Island Navy Yard.

The next day, she fired torpedoes at another of the cargo ships but could not learn the results of her attack, since she was forced to dive to escape the subchaser's depth charges.

[23] On her ninth war patrol (now commanded by Philip W. Garnett, Class of 1933),[24] 15 October to 9 December, Sargo operated off Formosa and in the Philippine Sea.

[27] After refit in Pearl Harbor, the veteran submarine departed on her eleventh war patrol on 7 April, along the southern coasts of Kyūshū, Shikoku, and Honshū.

On 26 April, she torpedoed and sank the cargo ship Wazan Maru in Kii Suido, approaching Osaka Bay.

She returned to Pearl Harbor on 26 May and steamed east to the west coast of the United States for a major overhaul at Mare Island Navy Yard.