Submarine USS S-15 (SS-120) was authorized to be built by theUnited States Congressional Act of 4 March 1917 which stated in part: “….of the vessels authorized in the ‘Act…’ approved August twenty-ninth, nineteen hundred and sixteen, the construction of the following vessels shall be begun as soon as practical at a cost exclusive of armor and armament not to exceed the following amounts:… eighteen coast submarines to have a surface displacement of about eight hundred tons each, $1,300,000 each,….”

The keel of USS S-15 (SS-120) was laid down on 13 December 1917 by the Lake Torpedo Boat Company at Bridgeport, Connecticut. The submarine was christened by Mrs. Simon Lake and launched on 8 March 1920. The S-boat was commissioned on 15 January 1921 with Lieutenant Commander David R. Lee in command.

When commissioned, the S-3 Class coastal and harbor defense submarine was 231′ in length overall; had an extreme beam of 21’10”; had a normal surface displacement of 876 tons, and, when in that condition, had a mean draft of 13’1″. Submerged displacement was 1,092 tons. The submarine was of riveted construction. The designed compliment was four officers and thirty-four enlisted men. The boat could operate safely to depths of 200 feet. The submarine was armed with four 21-inch torpedo tubes…installed in the bow. Twelve torpedoes were carried. One 4-inch/50 caliber deck gun was installed.

The full load of diesel oil carried was 36,950 gallons, which fueled two 1,000 designed brake horsepower diesel engines manufactured by the Busch Sulzer Brothers Diesel Engine Company at Saint Louis, Missouri …which could drive the boat, via a diesel direct drive propulsion system, at 15 knots on the surface in relatively calm seas.

Power for submerged propulsion was provided by a main storage battery, divided into two sixty-cell batteries, manufactured by the Electric Storage Battery Company (EXIDE) at Philadelphia, Pennsylvania…which powered two 600 designed brake horsepower main propulsion motors manufactured by the Westinghouse Electric Company at Pittsburgh, Pennsylvania…which turned propeller shafts…which turned propellers…which could drive the submarine at 11 knots for a short period of time when operating beneath the surface of the sea. Slower submerged speeds resulted in greater endurances before the batteries needed to be recharged by the engines and generators.

Attached to Submarine Division 18, USS S-15 (SS-120) departed the United States Naval Submarine Base at New London/Groton, Connecticut, on 31 May 1921, and transited…via the Panama Canal, California, the Territory of Hawaii, and Guam…to the Philippine Islands. The S-boat arrived at Cavite on the Island of Luzon on 1 December 1921.

In 1922, the submarine departed Cavite on 11 October, visited Hong Kong from the 14th to the 28th, and returned to Cavite on 1 November.

Departing Manila on 15 May 1923, USS S-15 visited Shanghai, Chefoo, and Chinwangtao, before returning, via Woosung and Amoy, to Cavite…on 11 September.

In the summer of 1924, the submarine again visited China, returned to the Philippines, and was back in-port at Olongapo on 23 September.

USS S-15 departed Cavite on 29 October 1924 and transited to the west coast of the United States. The submarine arrived at the Mare Island Navy Yard at Vallejo, California, on 30 December 1924.

The S-boat remained at the Mare Island Navy Yard during 1925 and 1926…then operated along the west coast of the United States through 1927.

From February of 1928 into 1935, USS S-15 operated in the coastal waters of the Panama Canal Zone…although the S-boat visited Baltimore, Maryland, from 15 May to 5 June of 1933.

On 11 January 1935, the submarine departed Coco Solo in the Panama Canal Zone and transited to the Philadelphia Navy Yard at Philadelphia, Pennsylvania. Upon arrival, she commenced preparations to go out of active service. On 26 April 1935, USS S-15 was placed out of commission and moored in the reserve fleet at the Philadelphia Navy Yard.

With World War II clouds looming on the horizon, USS S-15 was taken out of mothballs and recommissioned on 3 January 1941 at the Philadelphia Navy Yard. Following voyages to Bermuda, the submarine operated in the Caribbean…basing at Saint Thomas in the United States Virgin Islands…from 31 October to 9 December of 1941.

The United States became an active participant in World War II following the Japanese attack on Pearl Harbor in the Territory of Hawaii on 7 December 1941.

USS S-15 assisted in the protection of the Panama Canal by patrolling in the coastal waters of the Panama Canal Zone from January of 1942 into December of 1943. The submarine then operated out of Guantanamo Bay, Cuba…through May of 1944; then returned to the water approaches of the Panama Canal during June of 1944. There, the S-boat patrolled through September of 1944; then operated out of Trinidad for the rest of that year.

USS S-15 based at Guantanamo Bay from January into March of 1945 while she provided services to vessels at Guantanamo Bay…and while she patrolled in the Caribbean Sea.

USS S-15 departed Guantanamo Bay on 23 March 1945 and transited to the United States Naval Submarine Base at New London/Groton, Connecticut. Upon arrival, the S-boat prepared to go out of service.

World War II officially ended on 2 September 1945 with the signing of the instruments of surrender by the Japanese on board battleship USS Missouri…which was anchored in Tokyo Bay, Japan, for that occasion.

USS S-15 (SS-120) was decommissioned on 11 June 1946 at the Philadelphia Naval Shipyard and struck from the Navy List.

On 4 December 1946, the S-boat was sold to the Potomac Shipwrecking Company of Maryland for subsequent scrapping.