The Battle of the Bismarck Sea: A Convoy Destroyed and Supply Routes Changed

After setbacks in Papua and Guadalcanal in early 1943, Japanese forces still sought to strengthen Lae, Salamaua and other positions on New Guinea’s northern coast. A January convoy had delivered troops to Lae, followed by an inland attack on Wau. For MacArthur’s Southwest Pacific command, cutting sea supply directly affected pressure on land.

Rear Admiral Masatomi Kimura’s escort assembled at Rabaul in late February with eight destroyers and eight transport-purpose vessels, including the naval auxiliary Nojima. They carried much of the Fifty-First Division, other troops and supplies. Departing during the night of 28 February–1 March, the convoy sailed west along New Britain’s north coast before turning into strait passages toward Huon Gulf and Lae.

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Allied intelligence warned in February of possible Japanese reinforcements for Lae. George Kenney’s air command and Ennis Whitehead’s forward headquarters prepared alternatives for direct passage to Lae, dispersal or diversion to Madang. Aircraft range determined which units could attack each stretch of sea, requiring preparation before the convoy was sighted.

American B-25 medium bombers gained stronger forward-firing armament. Crews practiced low-level attacks on wrecks near Port Moresby and trained with Australian Beaufighters and other types. Methods included skip bombing across the water and close-range attacks directly at ships’ sides. Storms obscured the convoy, but a B-24 found it on the afternoon of 1 March, after which reconnaissance aircraft maintained contact.

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On 2 March, the convoy remained chiefly within range of Allied heavy bombers. B-17 attacks sank Kyokusei Maru. Destroyers Yukikaze and Asagumo rescued approximately 850 people, quickly carried them to Lae and returned to the convoy. The operation was disrupted, although some reinforcements did reach their destination.

Crews observing from different altitudes and directions gave inconsistent counts and damage reports, sometimes identifying large destroyers as cruisers. Australian Catalinas continued surveillance overnight. Passing through the Vitiaz Strait and turning toward Huon Gulf brought the convoy into an area where Allied light and medium bombers could concentrate.

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An early Australian Beaufort torpedo attack achieved no hits. American and Australian aircraft then assembled near Cape Ward Hunt for the main coordinated strike. P-38 fighters engaged the Japanese air escort, B-17s bombed from higher altitude, and low-flying Beaufighters strafed decks to suppress antiaircraft positions. B-25s, A-20s and others followed with bombing attacks.

Combining low-level strafing and bombing made threats from different directions and heights difficult to counter. Flagship Shirayuki was badly damaged; the wounded Kimura transferred away. Arashio, Tokitsukaze and transport ships successively became disabled. Allied aircraft rearmed and attacked again that afternoon, although weather kept some formations from reaching the scene. Coordination in battle varied from the rehearsals.

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During the night of 3–4 March, American motor torpedo boats from Tufi sank an already damaged ship. Aircraft sank a damaged destroyer the next day. Over subsequent days, Allied aircraft strafed rafts, lifeboats and small craft carrying shipwreck survivors. Official histories also record Japanese fighters firing on parachuting American bomber crew. Attacks on people who had left aircraft or ships formed part of the battle.

Postwar reconciliation established losses of eight transport-purpose vessels and four destroyers, with four destroyers surviving. An Allied communiqué of 7 March had claimed all twenty-two ships destroyed and exaggerated deaths. Later American and Australian official histories revised Japanese deaths to approximately three thousand, including troops and ship crews. Most rescued survivors returned to rear areas. Specific estimates vary, but later research substantially corrected the wartime claims.

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Most reinforcements failed to reach Lae, and substantial equipment was lost with the ships. Japanese forces subsequently avoided equivalent large convoys directly to Lae, relying more on transfer through Wewak and Madang farther north, submarines, aircraft and small coastal barges. Lower capacities and difficult transfers constrained the Lae and Salamaua garrisons’ ability to sustain combat.

Allied forces still had to capture positions on land, and the New Guinea campaign continued. The naval-air battle combined reconnaissance, base development, crew training and attacks on shipping into effective transport interdiction. It made concentrated Japanese reinforcement harder and helped create conditions for subsequent operations against the northern coastal positions.

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