The Battle of the Bismarck Sea was a battle in the Pacific Campaign of World War II, between planes of the US Fifth Air Force and the Royal Australian Air Force, and a Japanese convoy carrying troops to Lae. The task force was destroyed in detail, and the Japanese troops losses were extremely high.

Background

On December 23, 1942, the Japanese high command decided to transfer about 100,000 troops from China and Japan to Lae in New Guinea to reinforce their forces there. This would allow the Japanese to fall back from their defeat at the Battle of Guadalcanal, which they ordered evacuated the next week. The troops were needed near Lae, where an Allied offensive was expected.

The move was not a small one — it was a heavy burden on Japanese shipping capability, but the high command thought it was necessary. By late February, the 20th and 41st divisions had been safely transported to Wewak. Next, the 51st Division was to be transported from the fortress port of Rabaul to Lae. This was very dangerous — Allied air power in the area was very strong, especially in the Dampier Strait , through which the ships would have to pass.

The convoy assembled had eight destroyers, eight troop transports, and was escorted by approximately 100 planes when it departed from Simpson Harbour in Rabaul on February 28, 1943. The commander officer of the 51st Division, Lieutenant General Hidemitsu Nakano , was aboard the destroyer Yukikaze, while Rear Admiral Kimura Masatomi , the head of the operation, was on a troop transport, Desron 3.

The battle

Although tropical storms hit the Solomon and Bismarck Seas from February 27 to March 1, the convoy, moving at a top speed of seven knots, was spotted north of Cape Hollman by the crew of a patrolling B-24 Liberator bomber at about 3:00 pm on March 1. However, US heavy bombers sent to the location failed to locate the convoy.

The next day at about 10:00 am another Liberator found the convoy, and clear skies allowed several flights of US B-17 Flying Fortress bombers to attack and sink possibly three merchant ships, including the Kyokusei Maru. A B-17 was shot down by a New Britain-based Mitsubishi Zero fighter, the pilot of which was seen to machine-gun the B-17 crew in both their parachutes or life vests [1]. Out of 1,500 troops being transported by the Kyokusei Maru, 800 were rescued from the water by the destroyers Yukikaze and Asagumo. These two ships then proceeded to Lae to disembark the survivors, and then rejoined the convoy the next day. The convoy, without the troop transport and two destroyers, was attacked again that evening, with one troop transport sustaining minor damage.

PBY Catalina flying boats from No. 11 Squadron RAAF continued to trail and occasionally bomb the convoy over the night of the March 2, and at about 04:00 am on March 3, when the convoy was within range of the RAAF base at Milne Bay , Beaufort torpedo bombers from 100 Squadron took off. However, due to bad weather only two Beauforts found the convoy and neither scored any hits.

The convoy was now rounding the Huon Peninsula, bringing it into clearer conditions. A force of 90 Allied aircraft took off from Port Moresby and headed for Cape Ward Hunt; simultaneously 22 RAAF Bostons set off to attack the Japanese fighter base at Lae, reducing the convoy's air cover. Attacks on the base continued throughout the day.

At 10:00, 13 B-17s reached the convoy and bombed from medium altitude, causing the ships to disperse, and prolonging the journey.

Then 13 Beaufighters from No. 30 Squadron RAAF approached at low level, to give the impression they were Beauforts making another torpedo attack. The ships turned to face them and the Beaufighters were then able to inflict maximum damage on the ships' AA guns, bridges and crews, during strafing runs with their four 20mm (0.787 in) nose cannons and six wing-mounted .50 (12.7mm) machine guns.

Immediately afterwards, 13 US B-25 Mitchells, bombed from 2,000-3,000 ft. Then 12 specially-modified Mitchells attacked with a new technique called "skip bombing" — flying only a few dozen feet above the water. This allowed the bombs, when released, to skim across the water like a stone, reportedly claiming 17 hits. By this time half of the transport ships were sunk or sinking. As the Beaufighters and Mitchells expended their munitions, some USAAF A-20s joined the attack. Another five hits were claimed by B-17s from higher altitudes.

While the attack on the ships proceeded, 28 US P-38 Lightnings provided top cover, and 20 Japanese fighters were shot down for the loss of only three Lightnings. During the afternoon, further attacks from Mitchells and RAAF Bostons followed.

All seven of the remaining transports were sunk about 100 km southeast of Finschafen , along with the destroyers Shirayuki, Arashio, and Tokitsukaze.

Four of the destroyers picked up as many survivors as possible, and then retired back to Rabaul. The fifth destroyer, Asagumo, was sunk in a subsequent strike as it was picking up survivors from the Arashio.

Following orders from senior commanders, from the evening of March 3 until March 5, Allied PT boats and planes attacked Japanese rescue vessels, as well as survivors from the sunken vessels on life rafts and swimming in the sea. Many of these attacks were in breach of the Geneva Convention; however, Japan was not a signatory to the convention, and by 1943 there had been many reports of similar Japanese atrocities against both civilians and Allied personnel.

Aftermath

The battle was a disaster for the Japanese. Out of 6,900 troops who were badly needed in New Guinea, only about 800 made it to Lae. The Australian War Memorial states that 2,890 Japanese soldiers and sailors were killed.[2]

"A merciful providence guarded us in this great victory," said Douglas MacArthur in one of his communiques. He used the victory to request five divisions and 1,800 aircraft in preparation for his landings in northern New Guinea.

External links

• Brad Manera, Military Historian, Australian War Memorial, 2003, Battle of the Bismarck Sea, 2-4 March 1943
• Dr Alan Stephens, ?, "Battle of the Bismarck Sea"
• Geoff Hastwell, 2003, "The Battle of the Bismarck Sea"