Aspro was laid down on 27 December 1942 by the Portsmouth Navy Yard in Kittery, Maine; launched on 7 April 1943; sponsored by Mrs. William L. Freseman; and commissioned on 31 July 1943.
Aspro held shakedown training in the waters off Portsmouth, New Hampshire; Newport, Rhode Island; and New London, Connecticut.
She arrived at Pearl Harbor on 18 October and immediately began preparations for her first war patrol which would take her to waters around Formosa and Sakishima Gunto.
The rest of this patrol passed uneventfully, and Aspro retired to Pearl Harbor on 28 March after 54 days at sea.
At 05:54, she fired a spread of torpedoes at one freighter and, one and one-half hours later, saw the damaged ship lying dead in the water and sinking by the stern.
{15 May 1944 the Sinking ship "Jokuja Maru" 6,440 tons was sunk at 10.10N 131.25E} The submarine spent two weeks undergoing a refit before beginning her fourth patrol on 9 July.
After pausing at Darwin, Northern Territory on 16 July to top off her fuel tanks, she proceeded to the South China Sea.
Shortly thereafter, on 19 July, Aspro found a convoy of four medium-sized ships in company with five escort vessels off the west coast of Luzon and fired her torpedoes at 05:45 and heard a series of explosions.
On 28 July, Aspro sighted an anchored ship flying a Japanese flag and launched a spread of torpedoes.
The submarine heard three explosions, and her target emitted heavy smoke amidships and began listing to starboard and settling by the bow.
A week later, she encountered the moored ship again – hard aground, listing to starboard, and completely gutted by fire.
{This was the transport "Peking Maru" of 2,288 tons at 17.33N 120.21E} On 6 August, the submarine spotted two Japanese freighters and opened fire at 10:16.
While still in transit to the patrol area, she found her first targets on 30 September off the northeast coast of Luzon where she met a convoy of seven or eight vessels protected by four escorts.
{The 2 Oct 1944 credit was the cargo "Azuchisan Maru" of 6,888 tons at 18.25M 120.32E} Following this action, Aspro rendezvoused with Hoe and Cabrilla to form a wolf pack.
Her most important accomplishment of the patrol – which ended at Pearl Harbor on 11 February 1945 – was her rescue of four downed American aviators.
Her seventh and final patrol began on 25 June and covered waters south of the Japanese home islands.
On 8 July, she was assigned lifeguard duties in support of planes that had taken off from Iwo Jima for strikes on military targets in Japan.
Five days later, the submarine attacked and claimed to have sunk a Japanese tug with her final torpedo spread of the war.
For his "Conspicuous Gallantry" Freeman was awarded a Silver Star and a Purple Heart for wounds he received.
She arrived at San Francisco on 11 September for preservation work prior to being placed out of commission on 30 January 1946 and entering the Pacific Reserve Fleet in the Mare Island berthing area.
Aspro was recommissioned on 6 July 1951 and, for the next two years, operated out of San Diego, her new home port, and performed routine work along the west coast.
This routine was broken first by the 1959 movie Battle of the Coral Sea, starring Cliff Robertson, which was shot in part aboard Aspro, then by a deployment to the western Pacific in mid-1959.