At approximately 1:00 AM on October 8th, 1944, while in the Celebes Sea en route to Australia, BECUNA sees her first combat action that results in damage to enemy shipping. Two additional American submarines, USS BAYA and USS HAWKBILL, are also operating in the area. Spotting her first target, BECUNA sets her sights on a Japanese tanker. She makes a submerged attack in the dark using her periscope, and fires four torpedoes. Two hit, and skipper Lt. Commander Henry Sturr reports the ship sinks. However, postwar investigations reveal the ship, the 6,863-ton KIMIKAWA MARU, is heavily damaged but survives BECUNA’s attack.

A few weeks later, BECUNA sees action again. October 17th, 1944, is a busy day for BECUNA and her crew. Around 5:00 PM, BECUNA launches four separate underwater attacks against a Japanese convoy. Her first victim is a 7,268-ton armed tanker, later revealed to be the SAN LUIS MARU. BECUNA fires twice, scoring two hits. The SAN LUIS MARU suffers medium damage but survives.

That same hour, BECUNA attacks again. This time her target is another tanker, the 1,943-ton TOKUWA MARU. BECUNA fires two torpedoes; both find their mark. The TOKUWA, though damaged, remains stubbornly afloat for the time being.

BECUNA quickly turns to two other targets. Still submerged in the dimming light, she fires three torpedoes at 7,500-ton transport, scoring two hits. BECUNA then brings another enemy vessel under her sights—a 4,000-ton cargo ship. She looses a single torpedo, which finds its mark. Despite their damage, neither vessel sinks.

Sometime after 6:00 PM, another American submarine, the USS HAWKBILL, encounters the doomed TOKUWA MARU, still limping from BECUNA’s two earlier hits. HAWKBILL fires a spread of four torpedoes, striking the TOKUWA twice. Mortally wounded from her four hits, TOKUWA MARU sinks by the stern. BECUNA ends her first patrol having damaged four enemy warships and assisted in the destruction of a fifth, for which she shared a ½ kill with HAWKBILL. Return to top.

Second War Patrol, November-January 1944
Area of Operation: South China Sea
Duration: 53 Days

On her second patrol, BECUNA again sees action. At about 7:00 AM on January 2nd, 1945, BECUNA, operating on the surface, opens fire with her deck guns on a small 300-ton vessel. The vessel is reported sunk, but no post-war source can be found to confirm the loss. Just six hours later, at about 1:00 PM, BECUNA sights a second enemy vessel—an 800-ton general-purpose vessel. Surfaced in broad daylight, BECUNA again opens fire with her deck guns. BECUNA reports sinking the vessel, though Japanese records later prove unable to confirm the kill. BECUNA ends her second patrol with two kills. Return to top.

Third War Patrol, February-April (?) 1945
Area of Operation: South China Sea
Duration: 46 Days

On February 22nd, 1945, at about 9:00 AM, BECUNA crosses paths with the 1,945-ton Japanese tanker NICHIYOKU MARU. Taking no chances, BECUNA makes a submerged attack by periscope and fires six torpedoes. Though only one strikes home, it proves sufficient to grant BECUNA her first—and only—successful torpedo attack of the war, plunging the NICHIYOKU MARU to the bottom of the South China Sea. Following the attack, BECUNA survives a savage depth-charging attack. Return to top.

Fourth War Patrol, May-June (?) 1945
Fifth War Patrol, June-July (?) 1945
Area of Operation: South China Sea
Duration: 39 Days, 36 Days, respectively

Though her crew could not know, the war effectively ends for BECUNA on her third patrol; by mid-1945, there are so few Japanese vessels left afloat that BECUNA makes little enemy contact at all during her fourth and fifth war patrols. BECUNA ends the war having sunk three Japanese ships, sharing a half-credit equally with the USS HAWKBILL for a fourth. Her efforts help send 4,988 tons of enemy shipping to the bottom of the Pacific. Return to top.

Wartime Attack Summary, Submarine BECUNA

The data below summarizes the wartime attacks resulting in the damage or destruction of Japanese shipping by Submarine BECUNA during World War II.

Oct 1944: KIMIWAWA MARU, Merchant Tanker, 6,863 tons, damaged
Oct 1944: SAN LUIS MARU, Merchant Tanker, 7,268 tons, damaged
Oct 1944 TOKUWA MARU, Merchant Tanker, 1,943 tons, sunk, ½ credit*
Oct 1944: [Unknown] Transport, 7,500 tons (est.), damaged
Oct 1944: [Unknown] Merchant Cargo Ship, 4,000 tons (est.), damaged
Jan 1945: [Unknown] Merchant Auxiliary, 300 tons, sunk
Jan 1945: [Unknown] Merchant Auxiliary, 800 tons, sunk
Feb 1945 NICHIYOKU MARU, Merchant Tanker 1,945 tons, sunk

*Credit shared with American submarine HAWKBILL

Total Enemy Tonnage Damaged: 25,631 tons

Total Enemy Tonnage Sunk (with HAWKBILL): 4,988 tons