She subsequently departed New Orleans 6 August, and steamed through the Panama Canal to the Pacific and arrived at Pearl Harbor on 22 September.

Following additional training the submarine sailed 9 October for her first war patrol, operating with Pintado and Atule in a coordinated attack group known as "Clarey's Crushers".

After repairs, the submarine departed Midway 20 April for her third war patrol and was assigned aircraft lifeguard duty off Marcus Island.

Responding to reports of flyers in the water north of the island, on 9 May Jallao braved shore batteries to move in and pick up five men in a raft, delivering them safely to Saipan on 12 May.

She then departed for the coast of Japan and more lifeguard duty as American heavy bombers stepped up their attacks on the home islands.

Jallao's home port was changed to New London in July 1955 and she got underway with British submarine HMS Alderney 7 August to take part in Joint Exercise "New Broom IV".

In the months that followed, she helped train Italian Navy ships and took part in fleet exercises, beginning the long voyage home in mid-January 1956.

The ship steamed through the Suez Canal, visited several countries of eastern and southern Africa, and crossed the South Atlantic to take part in exercises with Uruguayan and Brazilian destroyers.

Combined fleet exercises in the Caribbean occupied her through February; and, after coastal antisubmarine operations, she arrived Boston late in July for a short midshipman training cruise.

On 26 June 1974, Jallao was decommissioned, struck from the US Naval Register, and transferred (sold) under the terms of the Security Assistance Program to Spain.