Departing Milne Bay, New Guinea, on 13 November for her first war patrol, Ray searched the area north of the Bismarck Archipelago.

On the New Hanover-Truk shipping lane, she made radar contact with a three-ship convoy, escorted by three patrol craft.

Then, after evading the escorts' countermeasures, she followed the convoy and sank the converted gunboat Nikkai Maru with a spread of torpedoes.

On 1 January 1944, SS-271 intercepted two ships with escorts in the mouth of Ambon Bay, Java, and sank converted gunboat Okuyo Maru with three hits.

Three days later, following an unsuccessful attack on two cargo ships escorted by a Chidori-class torpedo boat, Ray returned to Fremantle.

A spread of four torpedoes damaged a tanker, but USS Bluefish crossed Ray's line of fire preventing a coup de grâce.

Overtaking the disorganized convoy, during a tropical squall the next day, Ray fired on two radar contacts scoring hits.

Ray dived deep to escape Japanese patrol aircraft, and the sinking was never confirmed by captured records.

On 18 August, off northern Balabac Strait, Philippines, Ray closed a large convoy protected by surface escorts and planes, fired six "tin fish" at a tanker, and dived as a destroyer raced in to counterattack.

During the action, Ray heard another violent explosion and the sounds of a ship breaking up, as the tanker Nansei Maru went down.

The submarine's sixth war patrol, 23 September to 8 December, took her to the familiar waters of the South China Sea.

Five days later, she destroyed the cargo ship Toko Maru with two direct hits and escaped a subsequent depth charge attack.

On 14 October, while making a crash dive to escape a Japanese patrol plane, Ray's conning tower was flooded by an improperly secured hatch, but she was brought under control before reaching 85 feet (26 m).

On the afternoon of 1 November, Ray closed a five-ship convoy, sinking the cargo ship Horai Maru No.

On the night of 4 November, the sub sighted a cargo ship with its superstructure aflame, from an earlier attack by USS Bream.

On the night of 14 November, Ray made a surface attack on a three-ship convoy, blowing up an 800-ton frigate with a direct hit in its magazines.

Her torpedoes ran beneath the targets, and the "freighters", a disguised hunter-killer group, converged on the area where Ray had dived, laying a depth charge pattern.

Returning to her homeport of Norfolk 26 May, she participated in joint United States-Canadian exercises off Nova Scotia in July and August.

The remainder of 1954 and 1955 were spent in fleet exercises, type training, and an overhaul at Charleston Navy Yard from April to November 1955.

The remaining months of Ray's operating schedule in 1956 and 1957 were involved in type training and fleet exercises in the Atlantic and Caribbean, including representing Submarine Force, U.S. Atlantic Fleet, at the International Naval Review at Hampton Roads in June 1957 and participating in the NATO Exercise "Strikeback" held off Scotland, France, and Portugal in September and October 1957.