Submarine torpedo boat USS A-4 was originally laid down as USS Moccasin (Submarine Torpedo Boat Number 5) on 8 November 1900 at Elizabethport, New Jersey, by the Crescent Shipyard of Lewis Nixon, a subcontractor for the John P. Holland Torpedo Boat Company of New York. The submarine was christened by Mrs. Rice and launched on 20 August 1901; and commissioned on 17 January 1903 at the Holland yard at New Suffolk, New York, with Ensign Frank L. Pinney in command.

When commissioned, the Plunger Class submarine displaced 107 tons; was 63'10" in length; had a beam of 11'11"; drew 10'7" of water when on the surface in diving trim; could make 8 knots on the surface and 7 knots submerged; was manned by 7 officers and men; and was armed with one 18-inch torpedo tube.

Assigned to duty at the Naval Torpedo Station at Newport, Rhode Island; USS Moccasin operated locally on principally training and experimental activities until assigned to the Reserve Torpedo Flotilla at Norfolk, Virginia, on 15 June 1904, in which unit she remained inactive for the next half decade. On 20 July 1909, the submarine torpedo boat was loaded on board collier USS Caesar, which sailed soon thereafter for the Philippine Islands. USS Moccasin's sistership, USS Adder (Submarine Torpedo Boat Number 3) was on board as deck cargo as well, lashed to the auxiliary's forward well deck. Arriving at Olongapo on 1 October, USS Moccasin was launched on 7 October.

Recommissioned on 10 February 1910, the submarine torpedo boat was assigned to the First Submarine Division, Asiatic Torpedo Fleet, basing in the Manila area.

Early in the period she was operating with the Asiatic Fleet,

USS Moccasin was renamed USS A-4 (Submarine Torpedo Boat Number 5) on 17 November 1911. During World War I, like her sisterships, she patrolled the entrance to Manila Bay and convoyed ships moving out of local waters. Later placed in reserve, USS A-4 was decommissioned at Cavite on 12 December 1919.

Designated as a target vessel, USS A-4 (which had been assigned the alphanumeric hull number SS-5 on 17 July 1920) was struck from the Naval Vessel Register on 16 January 1922.

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