After three years in “mothballs,” Atule was towed to the Portsmouth (N.H.) Naval Shipyard for reactivation and conversion to a Guppy 1-A type submarine. Outfitted with a snorkel to permit use of her engines while submerged and a smooth streamlined superstructure for added speed, Atule rejoined the fleet a stronger, more versatile warship. On 8 March 1951, the submarine was recommissioned, Lt. Comdr. Benjamin C. Byrnside, Jr. in command.
Assigned to Submarine Squadron 8 in New London, Atule conducted a shakedown cruise in the Caribbean and then participated in Fleet and NATO training exercises in the Atlantic and the Caribbean. On 9 February 1952, she departed New London for a tour of duty in the Mediterranean and participation in NATO Exercise “Grand Slam.” During the deployment, she visited Gibraltar, Malta, and Marseilles, before arriving back in the United States on 29 March.
After several months of extensive training and preparations Atule participated in LANTSUBEX I from 15 September to 11 October. During this operation, she found herself battling the high seas and 100-knot winds of Hurricane Charlie which at one poin t rolled her more than 60 degrees to port, washing the officer of the deck and the lookout off the bridge. With safety belts attaching them to the bridge, they were able to climb safely back on board.
On 19 November, Atule entered the Portsmouth Naval Shipyard for an overhaul. After the yard work had been completed she got underway on 4 April 1953 to resume normal operations. During LANTSUBEX II in October, she suffered a serious fire and lost p ropulsion for approximately six hours in very heavy seas. The submarine arrived in New London on 27 October for repairs, leave and upkeep. She recommenced operations late in January 1954, by sailing to St. Thomas, Virgin Islands, for the annual Operation “Springboard” exercise. Late in February Atule departed St. Thomas for the return trip. But for a two-week visit to the Fort Lauderdale, Fla., area to provide services to the Naval Ordnance Laboratory Test Facility, she remained in New London for five months. Upon her return to New London Atule operated in the local area until February 1955, when she entered the Philadelphia Naval Shipyard for an extensive overhaul which was completed in August. The submarine then resumed training and operat ions in the New London area. In July 1957, Atule cruised to the Mediterranean and operated with the 6th Fleet until October. She entered the Philadelphia Naval Shipyard in January 1958 and departed in July, sailing to a new home port, Key West, Fla ., where she was assigned to Submarine Squadron 12. During the fall of 1958, Atule became familiar with her new operating area by working with the Operational Development Force assisting in the development and evaluation of new submarine techniques and equipment. She also acted as a target in surface and air antisubmarine exercises. After a Christmas leave period, Atule conducted local operations until April 1959, when she participated in an Atlantic Fleet exercise and then resumed local drills.
In July 1960, Atule again cruised to the Mediterranean for surface-subsurface training with NATO forces which lasted until October, when she returned to the United States and entered the Charleston Naval Shipyard for a six-month overhaul. After completion of the yard work in April 1961, Atule spent 18 months alternating duty at Key West with service at Guantanamo Bay supporting training for the destroyer force in antisubmarine warfare.
In October 1963, the submarine entered the Norfolk Naval Shipyard for an overhaul which ended in February 1964. She returned to Key West and operated from her home port until July when she sailed for the Mediterranean to operate with the 6th Fleet. She re turned to her home port in November for routine operations.
In August 1965, Atule departed Port of Spain, Trinidad, in company with other United States warships for a goodwill cruise during which she circumnavigated the South American continent. Known as Operation “Unitas VI” this operation promoted cooperation between naval forces of the United States and the participating South American countries. Atule drilled with ships of the navies of Venezuela, Colombia, Ecuador Peru, and Chile as she transited the Panama Canal and headed south along the coast . On 16 October, the submarine entered the Strait of Magellan and arrived at Punta Arenas, Chile, the southernmost city of South America. As she headed north, Atule’s crew became ambassadors of good will in port calls to Puerto Belgrano, Mar del Pl ata, Rio de Janeiro, and San Salvador before disbanding the UNITAS VI task unit in Trinidad on 1 December. The submarine then sailed for home and arrived there on 6 December for a leave and upkeep period that lasted into 1966. She remained in nearby waters for training and routine operations until 5 July when she moved to Charleston for another overhaul.
Atule left the shipyard on 26 January 1967 and during the year was assigned to duties at the Prospective Commanding Officers School and Fleet Training Group at Guantanamo Bay as well as continuing local training. In February 1968, she headed for th e Gulf of Mexico and New Orleans to train naval reservists and to celebrate Mardi Gras. The submarine returned via St. Petersburg, Fla. to her home port, where she continued general operations until 1 October when she got underway for her last Mediterranean deployment. After almost four months of exercises with the 6th Fleet, Atule returned to the United States on 3 February 1969 and resumed her duties in the local area. On 29 August, Atule departed Key West for Philadelphia where she was placed in commission, in reserve, on 15 September. Reclassified AGSS-403 on 1 October, Atule was decommissioned on 6 April 1970 and her name was struck from the Navy list on 15 August 19i3. She was sold to Peru in July 1974, and renamed Pacocha (S 48).
