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Bismarck Archipelago

Relief
        map of Bismarck Archipelago

The Bismarck Archipelago is located northeast of New Guinea and northwest of the Solomon Islands and shares the terrible jungle terrain and rainsoaked tropical climate of both. The archipelago was discovered by Able Tasman in 1642 and rediscovered by William Dampier in 1686. German settlers began moving into the area in the 1860s and Germany annexed the archipelago in 1885. Australian troops drove the Germans out in September 1914, during the First World War, and Australia received a Class C mandate over the islands from the League of Nations on 9 May 1921.

The total land area is about 26,300 square miles (68,100 km2). New Britain is the largest island in the chain, with an area of 14,600 square miles (37,800 km2). There are superb anchorages at Seeadler Harbor in the Admiralty Islands and Rabaul on the northeast tip of New Britain, but only the latter had been developed to any extent by the end of 1941, with modest docking facilities and two airfields. There is also an anchorage at Kavieng on the northwest tip of New Ireland, but it was overshadowed by Rabaul throughout the war. Prior to the Pacific War, the chief economic activities were export of copra, timber, and turtle shells.

Besides being jungle-clad, the islands are rugged, with several active or dormant volcanoes. For example, the anchorage at Rabaul is a flooded caldera, and resurgent domes in the harbor area emitted quantities of steam and ash from time to time. Sulfurous fumes greatly reduced the habitability of the many underground fortifications build here by the Japanese during the war. There are no significant mineral resources on the islands.

The islands receive their heaviest rains during the northwest monsoon of October through April, but there is no real dry season. Tropical diseases such as malaria were common, particularly on New Britain.

The native population consisted of Melanesian tribesmen, with some Polynesian blood, who had largely converted to Christianity by 1942. However, there were still rumors of headhunting by tribes in the interior of New Britain. The region produced some copra and timber but remained largely undeveloped under the Australians. Large numbers of natives were contracted as laborers, particularly since Asian immigrant laborers were prohibited. Native laborer employment was regulated to ensure that natives were properly cared for during the time period of their contracts.

The Bismarcks were marked for occupation in the earliest drafts of the Japanese Navy plans for the Centrifugal Offensive, as part of the outer defense line against the expected American westward drive (Plan ORANGE).

CARTWHEEL

Rabaul was the strategic key to the Bismarcks. The Japanese recognized the value of the port, and seized it with forces staged from Truk early in the Pacific War.  Air attacks began on 4 January 1942 and elements of the South Seas Detachment began their landings on 23 January, rapidly driving back the 1390 men of the defending Australian 22 Battalion ("Lark Force") and taking the town and airfields. With Rabaul secured, the Japanese occupied the remainder of the Bismarcks more or less at their leisure. Kavieng was taken the same day as Rabaul, Bougainville was occuped on 30-31 March, and the Admiralties were occupied on 8 April 1942.

Allied strategy in the Southwest Pacific was initially focused on recapturing Rabaul. MacArthur envisioned a two-pronged counteroffensive (CARTWHEEL) with one prong coming up the Solomons and the other across the Dampier and Vitiaz Straits from New Guinea to New Britain. These operations began with the operations to secure Guadalcanal in the Solomons (7 August 1942) and to clear the northeast coast of New Guinea around Buna (19 November 1942.) Both tasks proved far more difficult than anticipated, becoming battles of attrition that lasted for months. The Buna area was not secured until 22 January 1943 and Guadalcanal was not secured until 9 February 1943.

At at the Pacific Military Conference of March 1943 in Washington, D.C., MacArthur's representative, Richard Sutherland, presented a revised plan for taking Rabaul (ELKTON III). This envisioned the capture of the Huon Peninsula in New Guinea and Munda on New Georgia, followed by the seizure of points in western New Britain and Bougainville. The Allies could then take Kavieng, if necessary, before the final assault on Rabaul. Japanese forces in the area were estimated at around 85,000 men and 383 aircraft, with another 11,000 men, 250 aircraft, and the main strength of Combined Fleet available for immediate reinforcement. In the longer term, the Japanese could dispatch another 615 aircraft and 10 to 15 divisions to the area if shipping could be found. (Japanese records show that this estimate was quite good, and that shipping available was about 300,000 tons to which perhaps another 100,000 tons could be added.) MacArthur demanded another five divisions and a tripling of the air strength in the theater in order to carry out his plan.

The Washington planners rejected any reinforcements beyond two or three divisions and a small number of aircraft, and the plan was scaled back accordingly. The final directive, issued 28 March 1943, called for Allied forces to advance as far as the Huon peninsula, western New Britain, and Bougainville by the end of 1943. Overall command would be given to MacArthur, with whom Halsey in the South Pacific would be expected to cooperate. Fortunately, there was enough mutual respect between the two men to make the plan work.

Japanese order of battle, June 1943

8 Area Army (Imamura; at Rabaul)     


17 Army (Hyakutake; at Shortlands)     



6 Division (Kanda; at Bougainville)


18 Army (Adachi; at Madang)



41 Division (Abe; at Wewak)



20 Division (Katagiri; at Madang)



51 Division (Nakano; at Lae)


6 Air Division
About 240 aircraft

38 Division (at New Britain)


65 Brigade (Matsuda; at New Britain)     

Southeast Area Fleet (Kusaka; at Rabaul)     


8 Fleet (Mikawa; at Shortlands)

 
 
Southeastern Detachment (Sasaki; at New Georgia)      



 
13 Regiment     




229 Regiment



8 Combined SNLF (Ota; at New Georgia)



7 Combined SNLF (Katsuno; at Santa Isabel)


11 Air Fleet (Kusaka; at Rabaul)
About 300 aircraft

1 CL
8 DD
8 SS

Japanese reinforcements

7 Air Division       
1943-7
4 Air Army (Teramoto)     
1943-8

Allied order of battle, June 1943

Southwest Pacific Area (MacArthur; at Port Moresby)     

 
ALAMO Force (Krueger)



41 Division



2 Engineer Special Brigade



158 Regiment



112 Cavalry Regiment



503 Parachute Regiment



12 Marine Defense Battalion


Allied Land Forces (Blamey)



3 Australian Division



9 Australian Division


Allied Air Forces (Kenney)


 
5 Air Force (Kenney)     



 
5 Bomber Command  (Ramey)   




5 Fighter Command (Wurtsmith)




 
67 Fighter Squadron





RAAFCAAF (Bostock)




9 Group (Hewitt)


Allied Naval Forces (Carpender)



TF 76 Amphibious Force (Barbey)     

South Pacific Area (Halsey; at Noumea)


3 Fleet (Halsey)
Reinforced with warships of Pacific Fleet when necessary


TF 31 Amphibious Force (Turner)




8 DD
36 PT
9 APD
3 AK
3 AP
15 LST
39 LCI
Loaned to MacArthur as needed


TF 33 Air Force South Pacific (Fitch)       Total strength approximately 258 fighters, 193 bombers, 82  heavy bombers, and 12 PBY



Solomon Islands Air Force (Mitscher; at Henderson Field)     



1 Marine Air Wing




2 Marine Air Wing



Army Forces South Pacific (Harmon)
About 275,000 men



Americal Division
25 Division
37 Division
43 Division


No combat experience
Limited operational experience



13 Air Force (Twining)


I Marine Amphibious Corps (Vogel)




1 Marine Division
2 Marine Division
3 Marine Division
1 Raider Regiment
6 Marine Defense Battalions
1 Marine Parachute Regiment
Loaned to MacArthur

Allied reinforcements

3 New Zealand Division     
1943-8

By the time the Allied South Pacific forces had completed the Solomons campaign by advancing through New Georgia (30 June 1943) and Vella Lavella (15 August 1943) to Bougainville (1 November 1943), and the Southest Pacific forces had finally cleared the New Guinea coast as far as Lae (16 September 1943) and  Finschhafen (22 September 1943) and crossed to Cape Gloucester (26 December 1943), it had become clear just how formidable a fortress the Japanese had made of Rabaul. The Allies chose to bypass Rabaul, which was neutralized by air power and left to wither on the vine. The Admiralty Islands were assaulted on 1 March 1944, the Green Islands on 15 February 1944, and Emirau on 20 March 1944 to forge the last links in the ring around Rabaul.

CARTWHEEL proved to be the decisive campaign of the Pacific War, breaking Japanese air power while pinning down the Japanese Navy until the massive U.S. naval expansion began coming off the ways in late 1943.

Battle of the Bismarck Sea


A-20 Havoc bombs a Japanese transport

U.S. Army. Via ibiblio.org

The Bismarck Archipelago encloses a body of water known as the Bismarck Sea, some 500 miles (800 km) from east to west and 300 miles (500 km) from south to north. According to Miller (1959), the Bismarck Sea received its name during the Second World War.

Following the defeat of the Japanese attack on Wau in February 1943, the Japanese feared a counterattack against Lae, which had a garrison of just 3500 troops. General Imamura and Admiral Kusaka decided to move a force of 6912 soldiers from from Nakano's 51 Division from Rabaul to Lae to reinforce the garrison. The convoy (Operation 81) would be timed to take advantage of bad weather for concealment, and a large number of fighters would be standing by to provide cover if necessary. Yamamoto reluctantly consented to allocate eight modern fleet destroyers to the operation. The cargo, which included provisions and drums of aviation gasoline, was carefully distributed among the ships and combat-loaded for rapid unloading. All the transports carried numerous boats for unloading and the crews were under orders to ignore air raids while doing so. It was estimated that the troops could disembark in six hours and the supplies could be unloaded in 48 hours. The convoy would not be able to advance at much better than seven knots, but by taking the route north of New Britain, the convoy commander, Kimura, hoped to deceive the Allies that the convoy was headed to Wewak. Air cover would be provided from Rabaul, Gasmata, and Lae by about 40 Navy and 60 Army fighters, with the two services assigned separate morning or afternoon shifts on each of the seven days the convoy was expected to be at sea.  Additional aircraft would raid the Allied airfields at Port Moresby and Milne Bay in an effort to pin down Allied air power. Two earlier convoys had suffered an average 25% transport losses, but the Japanese were prepared to accept the loss of up to half the transports in this convoy.

However, the Allies anticipated such a move, and Allied code breakers were able to decrypt messages giving important details of the convoy operation. Meanwhile Kenney, who was dissatisfied with the effectiveness of medium- and high-level attacks on previous convoys, had ordered a squadron of B-25 Mitchells modified as "commerce destroyers." Eight machine guns were installed in and around the noses of the aircraft, and they were been modified to increase their maneuverability, turning them intopotent low-level strafers. The crews were trained in low-level attacks using an old wrecked freighter near Port Moresby as a target. When the crews dropped their bombs at 100-200' (30-60m) altitude, the bombs would skip along the surface of the water, bouncing right over the target if the release was badly timed, but hitting the hull near the waterline if the timing was good. The training was hazardous; one aircraft crashed after colliding with the mast of target hulk. After two other aircraft were damaged by debris kicked up by their own bombs, the bombs were given five-second-delay fuses. A full-scale rehearsal of a coordinated antishipping strike took place on 28 February 1943.

By then the Japanese had the eight destroyers and eight transports loaded and ready to go. Conditions were judged favorable on 28 February and the convoy set out, closely hugging the northern coast of New Britain and well concealed by poor weather. On the afternoon of 1 March the weather cleared slightly and the convoy was sighted by an Allied patrol aircraft. However, the weather was still bad enough that subsequent flights that day over the convoy, including one by 7 B-17 Flying Fortresses of 321 Bombardment Squadron that had just raided Gasmata, were unable to make visual contact.

The convoy was picked up again the next morning by a B-24 Liberator from 320 Squadron which counted seven merchant ships and seven destroyers. This aircraft maintained contact until about 1015, when a force of 12B-17s and 17 other bombers which pressed their attacks from an altitude of 5000 feet (1500 m) in spite of the Japanese antiaircraft and fighter cover. The bombers were escorted by 16 P-38 Lightnings of 39 Fighter Squadron, which shot down three Japanese A6M Zero fighters attempting to intercept. Kyokusei Maru was hit by at least five bombs, which set off the cargo of munitions and sank the ship. Teiyo Maru and Nojima were also damaged. Kimura refused to retreat, instead detaching Yukikaze and Asagumo to make a high speed run to Lae and deliver 950 survivors from the sunken transport. 

It was at this point that Kimura made the decision that McAulay (1991) characterizes as having doomed the convoy. Kimura ordered his ships to circle for a time during darkness, so as to time their arrival at Lae for the next morning. All that night, the Allied air units carried out preparations for a mass coordinated strike in the morning, just as they had previously rehearsed. Meanwhile PBY Catalina patrol aircraft continued to track the convoy using their ASV radar and dropping the occasional (and occasionally defective) flare.

At 0100 the next morning, 3 March 1943, just as the two destroyers were rejoining the convoy, Kenney threw his Sunday punch. Although the convoy had cover from about 40 A6M Zeros, these were unable to cope with the 16 P-38 Lightnings, 13 Beaufighters, and masses of B-17s, A-20 Havocs, and B-25 Mitchells that came in at three different altitudes: the Lightnings at high altitude to engage the Zeros, the B-17s at medium altitude as they had the day before, and the other aircraft at very low altitude. For the first time, many of the low-level attackers were trained and equipped for skip bombing. Meanwhile, another 38 Allied fighters patrolled over Lae and prevented any Japanese fighters from joining the convoy from that airfield.

The Japanese ship captains ignored the Flying Fortresses and turned into the low-level attack, which they assumed was a torpedo attack. This left the ships highly vulnerable to being raked by the machine guns of the Australian Beaufighters, then skip bombed by the A-20s and B-25s. The effect was devastating: 28 of the 37 500-pound bombs dropped by the first wave scored hits, and by the end of the day, all seven remaining transports were sunk or crippled, along with four of the destroyers. Shirayuki was lost early in the attack, when a bomb hit detonated her aft magazine. Aiyo Maru suffered two bomb hits that destroyed a boiler and ignited munitions and gasoline, with the fires quickly raging out of control. Oigawa Maru was likewise hit amidships by a bomb that damaged the boilers and ignited fatal fires.  Tokitsukaze was crippled by four bomb hits, including a hit in the engine room that her commander mistook for a torpedo hit. Arashio suffered three hits that destroyed her bridge and killed most of her engineering crew, and the ship turned out of control, ramming and crippling Nojima, which had already been hit by at least two bombs. Teiyo Maru was severely damaged by 20mm cannon fire, then crippled by two bomb hits that set off fires in drums of aviation fuel on her stern. Taimei Maru was hit at least three times, including a hit on the bridge by an aircraft that came so close that the suvivors believed it had crashed into the ship. Shinai Maru was also fatally hit near the bridge. Kemb Maru, with its load of volatile fuel, was hit and sank within five minutes. Allied losses were just three Lightnings and two bombers out of 335 aircraft participating in the battle. The Japanese lost 25 aircraft. 

The crew of one of the Allied bombers that was shot down took to their parachutes, only to be machine gunned by Japanese fighters. This was witnessed by some of the Allied pilots, and the story quickly spread through the air units that night, contributing to the willingness of the pilots to engage in the slaughter that was to come.

By 1030 the Allied strike was over. The surviving Japanese destroyers rescued as many survivors as they could, then withdrew at about 1130, except for Asashio. When the Allied aircraft returned at 1500, they found four or five transports and Arashio in a rough line from east to west, all burning, with Asashio to the north rescuing survivors and Tokitsukaze some distance away slowly sinking. The Allied strike was weakened by deteriorating weather, but it was still strong enough to smother Asashio with bomb hits and score additional hits on Arashio, Tokitsukaze, and some of the crippled transports. 

That night, American PT boats PT-143 and PT-150 finished off the crippled Oigawa Maru, the last of the transports still afloat, while Yukikaze returned to rescue a few more survivors from Arashio. The last of the damaged ships still afloat, Asashio, was scuttled the next day by Japanese aircraft.

The Allies reasoned that the survivors could not be permitted to make it to shore to join the Lae garrison; and, since Japanese soldiers did not surrender, they would have to be killed. Thus the morning of 4 March 1943 saw the start of a sickening slaughter of survivors in the water or on boats by aircraft and PT boats. Some pilots, inflamed by the machine gunning of the bomber crew and by other atrocity stories, carried out the mission with enthusiasm; others were repulsed by the slaughter; but none seem to have questioned its necessity. However, some 2734 men were rescued by Japanese destroyers and submarines, and a few hundred others escaped the slaughter to reach shore. At least 300 who landed in Allied territory were killed or captured. One boatload of survivors drifted as far as Guadalcanal, where they were killed by an American patrol.

Some 3664 soldiers from 51 Division were lost in the battle. The Allies lost thirteen killed, twelve wounded, and four aircraft shot down. The Japanese decided to risk no more convoys, and turned to barges and submarines to reinforce their garrisons in northeast New Guinea.

Japanese order of battle

8 Fleet (Mikawa)


Lae Resupply Convoy (Kimura)     
Carrying 6912 men, 12 antiaircraft guns, 21 artillery pieces, seven large  mortars, and 138 vehicles. Equipped with 38 landing craft.
 
 
DD Shirayuki
Sunk. Carried 29 passengers.


DD Arashio
Sunk. Carried 150 passengers.


DD Asashio Sunk. Carried 150 passengers.


DD Tokitsukaze
Sunk. Carried 150 passengers, including Adachi Hatazo, 18 Army commander.


DD Yukikaze Carried 150 passengers, including Nakano Hidemitsu, 51 Division commander.


DD Uranami Carried 150 passengers.


DD Shikiname Carried 150 passengers.


DD Asagumo Carried 29 passengers.


AP Teiyo Maru (6869 tons, 12 knots, two heavy AA guns, two light AA guns, one field gun)     
Sunk. Carried 1923 passengers and vehicles and equipped with 6 landing craft.


AP Shinai Maru (3793 tons, 9 knots)
Sunk. Carried 1052 passengers, artillery, and aircraft materials and equipped only with ship's boats.


AP Kembu Maru (953 tons, two machine guns)
Sunk. A "sea truck" carrying 50 passengers and 1650 drums of gasoline.


AP Oigawa Maru (6493 tons, two heavy AA guns, one field gun)
Sunk. Carrying 1324 passengers, artillery and vehicles, and equipped with 8 landing craft.


AP Taimei Maru (2883 tons, two light AA guns, twom achine guns, one field gun)     
Sunk. Carrying 200 passengers and equipped with 11 landing craft.


AP Kyokusei Maru (5493 tons, 10.5 knots, four heavy AA guns, one field gun)     
Sunk. Carrying 1203 passengers, artillery and vehicles, and equipped with 4 landing craft.


AP Aiyo Maru (2746 tons, 2 heavy AA guns, 2 light AA guns, one field gun)     
Sunk. Carrying 252 passengers, 65000 cubic feet (1850 m3) of munitions and provisions, and equipped wth 5 landing craft.


AP Nojima (4500 tons)
Sunk. Carrying provisions and 908 men of the 5 Yokosuka and 2 Maizuru SNLF.

25 Air Flotilla (Uwano)
Capable of mustering about 40 A6M Zeros for combat air patrol during each of the Navy's half-day shifts.


204 Air Group



252 Air Group



253 Air Group



582 Air Group

18 Army (Adachi)
Capable of mustering about 60 Ki-43 "Oscar" for combat air patrol during each of the Army's half-day shifts.

1 Air Regiment

11 Air Regiment

Allied order of battle

Allied Air Forces, Southwest Pacific (Kenney; at Dobodura, Gili Gili, and Port Moresby)     

 
5 Air Force (Kenney)

 
3 Attack Group (at Port Moresby)




8 Attack Squadron (at Kila Field)
A-20 Havoc



13 Attack Squadron (at Schwimmer Field)     
B25 Mitchell



89 Attack Squadron (at Kila Field)
A-20 Havoc



90 Attack Squadron (at Durand Field)
B25C-1 Mitchell. Specially modified and trained for skip bombing.


35 Fighter Group (at Port Moresby)




39 Fighter Squadron (at Schwimmer Field)
P-38 Lightnings


38 Bombardment Group (at Port Moresby)




71 Bombardment Squadron (at Durand Field)     
B25 Mitchell



405 Bombardment Squadron (at Durand Field)     
B25 Mitchell


43 Bombardment Group (at Port Moresby and Mareeba)




63 Bombardment Squadron (at Jackson's Field)     
B-17 Flying Fortresses



64 Bombardment Squadron (at Jackson's Field)      B-17 Flying Fortresses



65 Bombardment Squadron (at Jackson's Field)      B-17 Flying Fortresses



403 Bombardment Squadron (at Mareeba)
B-17 Flying Fortresses


49 Fighter Group (at Port Moresby)




7 Fighter Squadron (at Durand Field)
P-40 Warhawk



8 Fighter Squadron (at Kila Field) P-40 Warhawk



9 Fighter Squadron (at Schwimmer Field)
P-38 Lightnings


90 Bombardment Group (at Port Moresby)     




320 Bombardment Squadron (at Jackson's Field and Ward's Field)     
B-24 Liberators



321 Bombardment Squadron (at Jackson's Field and Ward's Field)      B-24 Liberators


9 Group RAAF (at Port Moresby and Milne Bay)




22 Squadron (at Ward's Field)
A-20 Boston



30 Squadron (at Ward's Field)
Beaufighter



100 Squadron (at Gili Gili)
Beaufort
Naval Forces, Southwest Pacific (Carpender)


Motor Torpedo Boat Striking Force



PT-66



PT-67


PT-68


PT-121


PT-128


PT-143


PT-149


PT-150
A squadron was typically 12 to 15 aircraft.

References

Bradley et al. (1992)

Gamble (2010)

Hata et al. (1989, 2002)

Iriye (1987)

McAulay (1991)

Miller (1959)

Morison (1950)

Rottman (2002)

Spector (1985)



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