Biak

Biak is the largest of the Schouten Islands, located in a large gulf in the north coast of western New Guinea. It is about 45 miles (72 km) long and 25 miles (40 km) wide. The somewhat smaller island of Soepiori is located to the northwest, across a very narrow strait, and the Padaido Islands are scattered to the southeast. Biak itself is mostly a low plateau covered with jungle, but there is a coastal plain on the south with considerable flat ground suitable for airfields. There are no natural anchorages and the island is almost completely surrounded by a formidable reef. The administrative center was Bosnik, on the southeast coast, where the reef was a bit narrower and was crossed by two stone jetties. There is a 200 foot (60 m) escarpment extending from east of Bosnik to Mokmer. This escarpment is about 500 yards (460 m) inland along most of its length, but comes close to the shore at Parai, leaving just enough room for a road. The indigenous population numbered about 25,000 in 1944.

The Japanese occupied the island in the spring of 1942 and built an airfield at Mokmer (136.107E 1.189S) capable of operating bomber aircraft. There were substantial concentrations of dual-purpose and antiaircraft guns at both Mokmer and Bosnik by 1944.

The Battle of Biak

Following their invasion of Hollandia, the Americans discovered that it would take many months to make the airfields at Lake Sentani capable of supporting heavy bombers. Aerial reconnaissance revealed that Biak was the nearest promising location for such airfields along MacArthur's line of advance. Aircraft based here would be well situated to support Nimitz' landings on the Marianas and Palau. MacArthur therefore ordered an expedited assault schedule on 10 May 1944, with a preliminary assault at Wakde on 17 May to secure airfields for local air cover and an assault on Biak ten days later. The landings were to be carried out by 41 Division  (Fuller) with the naval forces commanded by Fechteler.

Aerial reconnaissance showed that the reef offshore of Mokmer was unfavorable for the passage of landing craft, and the decision was made to land at Bosnik, where the terrain was more favorable. However, this meant that the landing force would have to advance along the coast road at the foot of the escarpment to reach the airfields at Mokmer. Because conventional landing craft would not be able to cross the reef even at Bosnik, the landing plan called for six LSTs to launch 63 LVTs and 25 DUKWs to bring the first four waves ashore. Subsequent echelons would land at the jetties from 15 LCIs. Engineers and their equipment would be landed on the reef early in the invasion from eight LCTs to prepare beaching ramps for LSTs carrying tanks.

The LVTs were manned by 542 Engineer Boat and Shore Regiment while the DUKWs were manned by African-American troops. The DUKW drivers were hastily trained to operate out of LSTs at the rehearsal held at Hollandia on 23 May 1944. They performed well in the actual landing in spite of considerable confusion.

Preliminary air strikes were carried out by both 5 and 13 Air Forces from Nadzab and the Admiralties on 17 May 1944. A total of 99 B-24 Liberators participated in these raids. Strikes continued almost daily until the landing date, and were joined the last three days by A-20s based on Hollandia. Other strikes were directed at Japanese airfields in the Vogelkop Peninsula west of Biak by Liberators from Darwin.

The landing force embarked most of 41 Division on 25 May 1944 and sailed that evening. It was joined next morning by the cruiser forces under Crutchley and Berkey. Fighter cover was provided by 5 Air Force from Wakde. Fechteler did not expect to achieve surprise, but the Japanese reconnaissance aircraft that detected his force the next day was not detected and Fechteler incorrectly believed he had achieved surprise after all.

The Japanese had expected an assault on Biak following the invasion of Hollandia, but not so quickly. Biak was supposed to be an important link in the Japanese perimeter, but the Japanese high command vacillated badly over whether to attempt to hold Biak or let it be sacrificed to buy time while a stronger perimeter was established further west. On 9 May 1944 Imperial General Headquarters announced that the perimeter was to be pulled back to Sorong, then changed its mind two days after the Allied landings and ordered a powerful naval response.

The Biak garrison consisted of almost 10,000 troops of whom 4000 were combat trained. These were mostly from 222 Regiment under Colonel Kuzume Naoyuki and included light tanks. The remaining troops included artillery, engineers, and 28 Special Base Force (Senda) with about 1500 sailors. Kuzume expected the landings to take place near Mokmer and concentrated his forces accordingly. These included four 4.7" dual-purpose guns and a 6" coastal defense gun close to the beach. Other artillery, mortars, and automatic weapons were deployed on the escarpment behind Mokmer, with the strongest position in a set of limestone caves 1200 yards (1100 m) north of Mokmer airstrip. The Allies later discovered that these "West Caves" had room for a thousand men. Another strong point was located in a smaller cave system directly north of Mokmer village, east of the airstrip, while a third strong point with pillboxes was located just west of Parai. The latter two strong points were serendipitously located in ideal positions to ambush the American advance along the coast that actually took place.

Elements of 41 Division (Fuller) began landing at 0629 on 27 May 1944.  Opposition at Bosnik was light except for a troublesome 4.7" gun situated in the Mokmer strongpoint that damaged a destroyer and was not permanently silenced for several days.  However, the weather was dead calm, and the prelanding bombardment by ships and aircraft of 13 Air Force soon obscured the landing area with smoke and dust. The initial five waves were caught in a 2 to 3 knot current, and landed about two miles (3 km) west of the planned landing beach before destroyer Kalk located the stone jetties on radar and discovered the mistake. The intial wave found itself in a mangrove swamp but quickly regrouped, and the sixth and subsequent waves were directed to the correct beach. The jetties were found to be in good condition and the remainder of the landing went according to plan. By nightfall, about 12,000 troops, 12 tanks, 18 artillery pieces, 500 vehicles, and 1400 tons of supplies were ashore. 186 Regiment was able to advance from the swamp to the coastal road and 162 Regiment was ashore on the correct beaches. 186 Regiment secured the beachhead while 162 Regiment drove throught their lines and began a rapid advance towards Mokmer, reaching Parai before digging in for the night.

Japanese aircraft put in a modest appearance during the first day. Four fighters appeared over the airstrips at 1100 but quickly retreated. Two fighters and four bombers appeared late in the afternoon and succeeded in hitting an LST with bombs that proved to be duds. Three of the bombers were shot down, but one succeeded in crashing into SC-699, which was set on fire and suffered two dead and eight wounded before the fires were put out and the subchaser salvaged.

MacArthur had discounted accurate intelligence showing 11,000 Japanese troops and light tanks on the island, believing there were not more than 2000 defenders. This intelligence was confirmed when 162 Regiment began to close on the airfield on the morning of 28 May 1944. The Japanese defenders suddenly opened fire from the Mokmer and Parai strong points, ambushing the American column and cutting its communications at Parai. Destroyer gunfire was unsuccessful in driving the Japanese back during the night. The next morning, the Japanese counterattacked from the west in battalion strength with supporting light tanks, and by noon it was clear that 162 Regiment was in an untenable position. By then the Americans had brought up Sherman medium tanks, which completely outclassed the Japanese machines and were able to cover the evacuation of 162 Regiment in LVTs.

Fuller called for reinforcements for an attack to clear the escarpment. He was given two battalions of 163 Regiment from Wakde, and during the two days it took to bring up these reinforcements in LCIs, 162 Regiment regrouped and rested. The attack resumed on 1 June 1944, with 186 Regiment advancing along the inland plateau while 162 Regiment resumed its drive along the coast. It took a week for Fuller's division to take Mokmer airfield, which remained under fire from the Japanese positions in West Caves until 13 June. By then MacArthur's patience had run out, and on 15 June Fuller was relieved by Eichelberger. Borokoe and Sorido airfields were taken until 20 June and Mokmer begin operating fighters on 22 June. Organized Japanese resistance was not broken until 28 June, when the West Caves were finally reduced, and mopping up continued until 20 August.

The Americans suffered casualties of 474 dead or missing and 2428 wounded. An epidemic of scrub typhus contributed another 3500 casualties. The Japanese garrison was annihilated except for about 220 prisoners.

Operation KON

The Japanese high command reacted strongly to the Biak invasion, which threatened to disrupt plans for a decisive battle in the central Pacific (A-Go.) Ozawa's Mobile Fleet, the main striking power of the Japanese Navy, had already assembled at Tawi Tawi in anticipation of the battle. However, the Japanese Army had written off Biak, and the Navy had allocated only the 18 aircraft of 23 Air Flotilla (Ito) at Sorong to repel any attack on Biak.

The Navy began concentrating its land-based air power in western New Guinea on 28 May 1944, ordering an additional 70 fighters and 20 bombers from Japan and the Marianas to join 23 Air Flotilla. Another 20 bombers, 8 reconnaissance aircraft, and 48 fighters were redeployed from the Carolines on 31 May. By then orders had been hastily prepared for Operation KON to relieve Biak.

The Japanese assembled a strong force around three heavy cruisers, a light cruiser, eight destroyers, two minesweepers, and battleship Fuso to transport the 2500 men of the Army's 2 Amphibious Brigade from Zamboanga to Biak. Since only one transport (a Japanese LST) was available, most the troops were embarked on the warships. The troops embarked on 31 May and expected to debark at Biak on 3 June. Air cover was to be provided by and additional troops were to be brought in on barges from Manokwari by Southwest Area Fleet.

KON kicked off with a large Japanese air raid against a group of 8 LSTs unloading at Bosnik on the afternoon of 2 June 1944. The Japanese mustered 54 aircraft for the raid and encountered no Allied fighter opposition due to inclement weather over Wakde and Hollandia. However, antiaircraft fire from ship and shore was extremely heavy and the Japanese lost 12 aircraft while inflicting only slight damage on one LST.

That night the Japanese surface force, divided into three groups, set out for Biak. By noon the next day they were under observation by American Liberators. The loss of surprise, combined with mistaken intelligence reporting an American carrier off Biak, prompted Toyoda to suspend the operation. Fuso, two heavy cruisers, and two destroyers returned to Davao, only to have destroyer Kazagumo sunk by submarine Hake at the harbor approaches. The remaining ships proceeded to Sorong, disembarking their troops on 4 June 1944. Unknown to the Japanese, the American reconnaissance was directed by Ultra decrypts.

The Japanese staged a second raid against Biak on 3 June 1944. Three destroyers, eight LCTs, and four LCIs off Bosnik were attacked by 32 Zeros and 19 bombers. The attackers were detected on radar at 1100 and the ships were able to avoid serious damage by violent maneuvers. Allied fighters arrived at 1125 (after being delayed by weather) and drove off the remaining Japanese aircraft. The Japanese lost 11 aircraft but were promptly reinforced by another 70 aircraft from the Marianas.

By then Kinkaid had concluded that the Japanese meant to make a major naval effort to relieve Biak. Crutchley was ordered to refuel, then take Berkey's cruiser group under his command, and the combined cruiser force had reached a point 25 miles north of eastern Biak by 1900 on 4 June 1944. All other Allied forces were ordered to clear the area. The Japanese had sighted the Allied surface force, and they launched a raid that arrived at 1740. One light cruiser was slightly damaged.

Crutchley had intelligence that the Japanese meant to land on the west coast of Biak, and he chose to sweep the south and west coasts of the island, barely avoiding a friendly fire incident when he passed the American shore batteries at Bosnik. No Japanese surface force was encountered and Crutchley retraced his course back to his patrol station northeast of Biak. Here he was attacked by four Japanese night torpedo bombers, which inflicted no damage. However, the Japanese launched a second night raid by two bombers against Wakde that caught over a hundred Allied aircraft parked closely together on the runway. This raid inflicted very heavy damage and put the airfield out of action for several days. So embarrassing was the episode that the official U.S. Air Force history barely mentions the raid and quotes no casualties, but at least two-thirds of the aircraft on the island were put out of action.

The Japanese made a second attempt to run in reinforcements on three landing barges towed by six destroyers. Two cruisers remained off the western tip of New Guinea to await developments while 23 Air Flotilla was directed to provide fighter cover. The reinforcement flotilla embarked 600 troops at Sorong and sailed for Biak at midnight on 7 June. However, it was spotted by Allied aircraft at 1245 the next day. In a low-level strafing attack by 10 B-25s, the Allied aircraft sank destroyer Harusame and slightly damaged three others.  Sakonju pressed on with the five surviving destroyers, but at 1900 he received a report that an Allied task force was racing to intercept him. Again, Ultra decrypts had warned the Allies.

Crutchely had been delayed by maneuvers to evade Japanese snoopers, and his force did not arrive off the west coast of Biak until 2200 on 8 June 1944. Shortly thereafter a PB4Y spotted Sakonju's force 60 miles (100 km) to the north-northwest. Crutchely ordered a turn to the north to cross the Japanese "T", but one of his destroyer divisions, DesDiv 42, ignored the order and raced towards the Japanese. The two forces sighted each other on radar at about 2320, and Sakonju promptly launched torpedoes and fled. The commander of DesDiv 42 radioed a warning to Crutchley, which was confirmed when one of the "fish" passed close astern of cruiser Boise. By then Crutchley's remaining destroyers were also in hot pursuit of the Japanese. Though no torpedo hits were inflicted on the Allies, they were unable to catch the fleeing Japanese force, although the two forces came close enough to exchange gunfire and for the Japanese to launch another wave of torpedoes. The Allies finally gave up the pursuit at 0230, lest they be mistaken for Japanese ships by their own aircraft when daylight came.

The Japanese had cast off the three landing barges early in the action. They were fired on by the American destroyers in passing, but the barges apparently made it to shore and landed a few reinforcements on Biak. However, the majority of the 600 troops in the reinforcement group were taken back to Sorong aboard the Japanese destroyers.

Finally, by 11 June 1944, the Japanese assembled an armada off Halmahera that included both Yamato and Musashi. This powerful force was scheduled to arrive at Biak on 15 June, deliver a heavy bombardment, and land its troops, but this operation was called off on 12 June when heavy air strikes against the Marianas indicated that Spruance would soon begin his landings there. It has been suggested that the Japanese would have done better to stay with their Kon plan, which would probably have inflicted a serious defeat on the weak American naval forces off Biak, rather than send the super battleships north to a battle to which they contributed little. As it was, 23 Air Flotilla got in a final shot before being withdrawn to Palau, inflicting serious damage on destroyer Kalk in a raid by four aircraft on the morning of 12 June.

The Japanese subsequently managed to slip perhaps 1100 troops in barges from Noemfoor through the Allied blockade to Biak.

Aftermath

During the battle, a Japanese naval radio unit ran into an American patrol and lost several codebooks. This prompted the Japanese to make emergency changes in their radio procedures, which slowed down their communications just as the Battle of the Philippine Sea was getting under way.

Engineers had begun improving the facilities at Bosnik on the first day of the landing. On 30 May 1944 a naval demolition team blasted a 5 foot (1.5 m) deep channel through the reef to allow LCMs and LCVPs to land directly on the beach. By 17 June an airstrip had been completed on Owi and on 22 June the first fighters were operating from Mokmer airstrip.

Allied order of battle, 27 May 1944

References

Morison (1953)
Prados (1995)

Spector (1985)

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