World War II: Battle of the Bismarck Sea

Battle of the Bismarck Sea
US Air Force

The Battle of the Bismarck Sea was fought March 2-4, 1943, during World War II (1939 to 1945).

Forces & Commanders


  • Major General George Kenney
  • Air Commodore Joe Hewitt
  • 39 heavy bombers, 41 medium bombers, 34 light bombers, 54 fighters


  • Rear Admiral Masatomi Kimura
  • Vice Admiral Gunichi Mikawa
  • 8 destroyers, 8 transports, approx. 100 aircraft


With defeat looming in the Battle of Guadalcanal, the Japanese high command began making efforts in December 1942 to reinforce their position in New Guinea. Seeking to shift around 105,000 men from China and Japan, the first convoys reached Wewak, New Guinea in January and February delivering men from the 20th and 41st Infantry Divisions. This successful movement was an embarrassment to Major General George Kenney, commander of the Fifth Air Force and Allied Air Forces in the Southwest Pacific Area, who had vowed to cut off the island from re-supply.

Assessing the failures of his command during the first two months of 1943, Kenney revised tactics and embarked on a rapid training program to ensure better success against maritime targets. As the Allies set to work, Vice Admiral Gunichi Mikawa began making plans to shift the 51st Infantry Division from Rabaul, New Britain to Lae, New Guinea. On February 28, the convoy, consisting of eight transports and eight destroyers assembled at Rabaul. For additional protection, 100 fighters were to provide cover. To lead the convoy, Mikawa selected Rear Admiral Masatomi Kimura.

Striking the Japanese

Due to Allied signals intelligence, Kenney was aware that a large Japanese convoy would be sailing for Lae in early March. Departing Rabaul, Kimura originally intended to pass south of New Britain but changed his mind at the last minute to take advantage of a storm front that was moving along the north side of the island. This front provided cover through the day on March 1 and Allied reconnaissance planes were unable to locate the Japanese force. Around 4:00 PM, an American B-24 Liberator briefly spotted the convoy, but the weather and time of day precluded an attack.

The next morning, another B-24 spotted the Kimura's ships. Due to the range, several flights of B-17 Flying Fortresses were dispatched to the area. To help reduce the Japanese air cover, Royal Australian Air Force A-20s from Port Moresby attacked the airfield at Lae. Arriving over the convoy, the B-17s began their attack and succeeded in sinking the transport Kyokusei Maru with the loss of 700 of the 1,500 men on board. B-17 strikes continued through the afternoon with marginal success as the weather frequently obscured the target area.

Tracked through the night by Australian PBY Catalinas, they came within range of the Royal Australian Air Force base at Milne Bay around 3:25 AM. Though launching a flight of Bristol Beaufort torpedo bombers, only two of the RAAF aircraft located the convoy and neither scored a hit. Later in the morning, the convoy came into the range of the bulk of Kenney's aircraft. While 90 aircraft were assigned to striking Kimura, 22 RAAF Douglas Bostons were ordered to attack Lae through the day to reduce the Japanese air threat. Around 10:00 AM the first in series of closely coordinated aerial attacks began.

Bombing from around 7,000 feet, B-17s succeeded in breaking up Kimura's formation, reducing the effectiveness of the Japanese anti-aircraft fire. These were followed by B-25 Mitchells bombing from between 3,000 and 6,000 feet. These attacks drew the bulk of the Japanese fire leaving an opening for low-altitude strikes. Approaching the Japanese ships, the Bristol Beaufighters of No. 30 Squadron RAAF were mistaken by the Japanese for Bristol Beauforts. Believing the aircraft to be torpedo planes, the Japanese turned towards them to present a smaller profile.

This maneuver allowed the Australians to inflict maximum damage as the Beaufighters strafed the ships with their 20 mm cannons. Stunned by this attack, the Japanese were next to hit by modified B-25s flying at low-altitude. Strafing the Japanese ships, they also made "skip bombing" attacks in which bombs were bounced along the surface of the water into the sides of enemy vessels. With the convoy in flames, a final attack was made by a flight of American A-20 Havocs. In short order, Kimura's ships had been reduced to burning hulks. Attacks continued through the afternoon to ensure their final destruction.

While the battle raged around the convoy, P-38 Lightnings provided cover from Japanese fighters and claimed 20 kills against three losses. The next day, the Japanese mounted a retaliatory raid against the Allied base at Buna, New Guinea, but inflicted little damage. For several days after the battle, Allied aircraft returned to the scene and attacked survivors in the water. Such attacks were viewed as necessary and were partially in retribution for the Japanese practice of strafing Allied airmen while they descended in their parachutes.


In the fighting at the Bismarck Sea, the Japanese lost eight transports, four destroyers, and 20 aircraft. In addition, between 3,000 and 7,000 men were killed. Allied losses totaled four aircraft and 13 airmen. A complete victory for the Allies, the Battle of the Bismarck Sea led Mikawa to comment a short time later, "It is certain that the success obtained by the American air force in this battle dealt a fatal blow to the South Pacific." The success of Allied airpower convinced the Japanese that even strongly escorted convoys could not operate without air superiority. Unable to reinforce and resupply troops in the region, the Japanese were permanently put on the defensive, opening the way for successful Allied campaigns.

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Your Citation
Hickman, Kennedy. "World War II: Battle of the Bismarck Sea." ThoughtCo, Aug. 26, 2020, Hickman, Kennedy. (2020, August 26). World War II: Battle of the Bismarck Sea. Retrieved from Hickman, Kennedy. "World War II: Battle of the Bismarck Sea." ThoughtCo. (accessed June 3, 2023).