USS S-40, a 1062-ton S-1 class submarine, was built at San Francisco, California. Commissioned in November 1923, she served along the west coast and in early 1924 went to the Caribbean for a few months of fleet exercises. With several of her sister "S-boats", S-40 was sent to the Philippines during September-November 1924. Serving thereafter as a unit of the Asiatic Fleet, she participated in a regular program of peacetime operations in the Philippines and off the China coast.

S-40 was in Manila Bay when Japanese agression started the Pacific War on 8 December 1941. For most of the rest of that month she made patrols as part of the unsuccessful effort to defend the Philippines. On 23 December she attacked enemy invasion forces in Lingayen Gulf, but her torpedoes missed, and the submarine endured a punishing depth charging in return. Later in the month, she was ordered to leave the now untenable Philippine area and take up duty in defense of the Netherlands East Indies. When those islands fell to the seemingly invincible Japanese during February 1942, S-40 moved onward to Australia. She made three scoreless war patrols into the Solomon Islands and New Guinea areas during May-September then, in October and November, transited to Pearl Harbor by way of the Gilbert Islands.

Following overhaul on the west coast, in June 1943 S-40 was sent north to the Aleutians, where she conducted two patrols before incessant electrical problems and oil leaks caused her to be ordered back to the U.S. For the rest of World War II, the elderly submarine was employed on training service along the west coast. USS S-40 was decommissioned in late October 1945 and sold for scrapping in November 1946.