'Cyclone' was the US seizure of Noemfoor island, off the north-western end of New Guinea, by forces of General Douglas MacArthur’s South-West Pacific Area command (2 July/31 August 1944).

Noemfoor is a small island of elliptical, almost circular, shape with a diameter of about 11 miles (17.75 km) in Geelvink Bay in north-western New Guinea and, encircled by coral reefs, is located just to the north of Geelvink Bay, between Biak island and the eastern coast of the Vogelkop peninsula on the mainland of New Guinea halfway between Biak and Manokwari. The island was virtually undeveloped before the war, with a native population numbering about 5,000 persons who were visited about twice a year by ships of the copra and ironwood trades. There are no anchorages of any significance, and the island is surrounded by a coral reef with a few small boat passages. Most of the coast to the north, south and east is mangrove swamp. The island is relatively flat, with its terrain dominated by limestone and coral terraces, with a maximum elevation of 670 ft (204 m), but the terrain is somewhat broken in the south. The entire inland area of the 129-sq mile (335-km²) island is covered by jungle.

Noemfoor island was occupied in September 1943 by the Japanese, who immediately began to develop the island as a link in their defensive perimeter, largely through the construction of airfields. The majority of the local population having decamped into the hills to avoid conscription as labourers, the Japanese imported some 3,000 forced labourers from Java. The Javanese were very poorly treated, and only 403 were still alive when the Allies finished capturing the island.

According to the US Army official history, more than 3,000 men, women and children had originally been shipped from other parts of the Dutch East Indies to Noemfoor by the Japanese: most of these came from Soerabaja and other large cities on Java. These civilians were forced to construct roads and airfields, mostly by hand, and were provided with little in the way of food, clothing, shelter or medical attention. Many attempted to steal Japanese supplies, and were executed. Others died from starvation and preventable disease.

The Formosan labour unit had originally numbered about 900 men, who also worked on airfield and road construction on half of the rice ration issued to the Japanese troops. When they fell ill from exhaustion, hunger or tropical diseases, they were put in a convalescent camp with a still further halved food ration, inadequate shelter and blankets, and almost non-existent medical care.

Using this labour force, the Japanese turned Noemfoor island into a significant air base with three new airfields at Kornasoren toward the northern end of the island with a 5,000-ft (1525-m) runway, Kamiri on the north-western edge of the island with a 5,000-ft (1525-m) runway and Namber on the western coast of the island with a 4,000-ft (1220-m) runway.

Bombing of the island by the US Army Air Forces and Royal Australian Air Force began as early as April 1944.

At the time of 'Cyclone', the Japanese had a labour force of about 1,100 persons on the island: these comprised 600 men of the Formosan auxiliary labour unit and 500 civilian forced labourers from the Netherlands East Indies. The garrison in June 1944 comprised about 2,000 men, mostly of the 219^th Regiment and 222^nd Regiment, as well as a miscellany of service troops.

'Cyclone' was the penultimate 'hop' of the South-West Pacific Area’s leapfrogging amphibious westward advance along the northern coast of New Guinea, and was planned while the major strength Major General Horace H. Fuller’s (from June 1944 Major General Jens A. Doe’s) 41^st Division was still hotly engaged in 'Horlicks' on Biak island just to the east of Noemfoor island in Geelvink Bay. Biak had been invaded for several reasons including the South-West Pacific Area command’s requirement for advanced airfields from which Lieutenant General George C. Kenney’s 5^th AAF could support further land operations, and Biak contained one of the only two airfield complexes left to General Korechika Anami’s 2^nd Area Army.

However, the determination of the Japanese resistance meant that the 5^th AAF could not use Biak during June and July, and MacArthur decided on another landing in the same area to secure the airfields at Komasoren, Kamiri and Namber on Noemfoor, which Allied intelligence estimated to have a garrison, commanded by Colonel Suesada Shimazu, of some 2,000 men of Shimizu’s own 219^th Regiment (part of Lieutenant General Shunkichi Ikeda’s 35^th Division) and part of the 222^nd Regiment, as well as the labour force.

Noemfoor was also used as a staging area for Japanese troops moving to reinforce Biak, which was invaded and seized by the Allies in May/June 1944. Japanese open-topped barges could travel from Manokwari to Noemfoor, a distance of about 60 miles (100 km), in a single night.

Noemfoor was selected for invasion for four reasons: firstly, Allied commanders believed that Japanese troops equivalent to less than one battalion would be based there; secondly, the Allies were already experiencing a shortage of amphibious vessels and Noemfoor could be seized without large-scale operations; thirdly, it had the greatest number of useful airfields in the smallest area; and fourthly, the Japanese air defences in western New Guinea were almost negligible. (At the end of June 1944 the headquarters of the RAAF reported that although Namber and Kamiri airfields were serviceable, they were barely being used, and 'a possibly generous' estimate suggested that only 19 Japanese bombers and 37 fighters remained in New Guinea.)

MacArthur ordered the invasion of Noemfoor on 14 June 1944, with a target date of 30 June, but this was later moved back to 2 July.

The island’s defences were softened by some 8,000 tons of bombs dropped by aircraft of Air Commodore Frederick Scherger’s air component (the Royal Australian Air Force’s No. 10 Operational Group bolstered by the USAAF' 58^th and 348^th Fighter Groups and 307^th, 309^th and 417^th Bombardment Groups) and an intensive bombardment by the Australian and US cruisers of Task Forces 74 and 75 of Vice Admiral Thomas C. Kinkaid’s US 7^th Fleet, under the immediate command of Rear Admiral Russell S. Berkey, supported by 14 destroyers, before the 2 July landing of the 8,000-man invasion force, comprising largely the 158^th Regimental Combat Team of the 41^st Division under the command of Brigadier General Edwin D. Patrick, the chief-of-staff of Lieutenant General Walter C. Krueger’s 6^th Army: the regimental combat team was then at Wakde and was relieved by Major General Franklin C. Sibert’s 6^th Division to participate in the assault. The landing force also included the 27^th Engineer Battalion and the RAAF’s No. 62 Works Wing to make the airfields operational as quickly as possible. The 'Cyclone' task force was carried and landed by the landing craft tank and mechanised landing craft of Rear Admiral William M. Fechteler’s Task Force 77.2, of Rear Admiral Daniel E. Barbey’s Task Force 77, organised into three groups: 40 medium landing craft manned by the 3^rd Engineer Special Brigade from Finschhafen, eight tank landing craft escorted by three submarine chasers from Wakde, and a group of two infantry landing craft 1.

Krueger gave away tactical surprise by sending a large force of Alamo Scouts to Noemfoor on 22/23 June without informing Fechteler. The Japanese detected the Alamo Scouts and drove them off before they could gather much intelligence, and thus forewarned Shimizu, the Japanese commander, immediately concentrated his troops at Kamiri and began laying minefields. Fortunately for the US forces, however, this placed the Japanese in precisely the area which had been selected for the massive preliminary bombardment, which was to be carried out by five cruisers and 25 destroyers. Air support began with preliminary raids on 20 June against both Noemfoor itself and other Japanese airfields in the Vogelkop peninsula, and there was little opposition as the 23^rd Air Flotilla had been redeployed for the reinforcement of the Mariana islands group.

The preliminary bombardment was credited with being remarkably effective, as Japanese troops encountered ashore appeared to be stunned and were killed in large numbers by the small arms fire of the assaulting US infantry. However, it is likely the Japanese were also half-starved from lack of supplies. By the fall of night on 2 July, the Americans had landed 7,100 troops, almost 500 vehicles and 2,250 tons of supplies. Kamiri airfield was taken without difficulty, and was ready for the arrival of Allied aircraft on 6 July.

The invasion force met little resistance from the shattered Japanese and was thus able to take the north-western airfield without difficulty. The only serious Allied reverse of the battle was on 3 July. On the basis of mistaken intelligence resulting from prisoner interrogations that a 3,000-man Japanese reinforcement had landed on Noemfoor a week before the Allied landings, Patrick asked for a reinforcement by US paratroopers . One battalion of the 503^rd Parachute Infantry was therefore dropped over Kamiri airfield from aircraft flying two abreast, but the drop zone had not been cleared of vehicles and numerous paratroopers were injured by landings on top of bulldozers, trucks, and other vehicles. The two leading aircraft also approached the drop zone at too low an altitude as a result of faulty altimeters, and the airborne soldiers' parachutes had barely enough time to open before the paratroopers hit the hard coral runway. As a result the battalion suffered 72 casualties. Another battalion was dropped on the following from aircraft flying in single file at the correct altitude over a properly cleared runway, but the battalion nonetheless suffered 56 casualties from landings on the hard surface. The drop of the regiment’s third battalion was cancelled in favour of delivery by infantry landing craft. The casualties had been wholly unnecessary, both because the intelligence was incorrect and because the 34^th Infantry, with a full complement of heavy weapons, was at Biak, a mere 10 hours distant by sea.

The Americans took Kornasoren airfield on 4 July 1944. During the evening of the same day, the Japanese made their sole organised counterattack of the campaign but, falling on the US troops advancing on Nambur, this had been easily beaten back by 06.30 on the next morning. On 6 July a battalion of troops was transported in 20 LCMs from the main beach-head to Nambur and seized the airfield without opposition.

Following the devastating preliminary bombardment, Shimizu had ordered his troops to retreat to the eastern side of the island for possible evacuation. The retreat turned into a rout, however, and although the paratroopers assigned to mopping up duty had some difficulty pinning the main Japanese force, led by Shimizu, the remaining survivors, some 200 strong, had been trapped against the south-east coast by the middle of August. The local population emerged from the island’s deep interior at a time late in July and re-established contact with the Dutch civilian administration. The local leaders declared war on Japan and aided the Allied operation to locate and destroy the last Japanese elements on the island.

The island was declared secure on 31 August 1944.

The fact that the Japanese defence had been totally disorganised was reflected in the fact that by 6 July all three airfields were in US hands, and the operation was for all practical purposes completed on the following day. The battle cost the Allies 66 Americans killed or missing and a further 343 wounded, and something in the order of 1,714 Japanese killed or missing and a further 186 taken prisoner. The Americans also took some 550 Formosan and 403 Javanese labourers.

Work on the repair and construction of the airfields by RAAF and US Army engineers began on 2 July, and in the afternoon of 6 July an Australian squadron with Curtiss P-40 Kittyhawk fighter-bombers arrived at Kamiri, from which it supported the continuing operations on Noemfoor as the first of many Allied air force units to be based there.

Namber airfield was assessed as too rough and too poorly graded to be used successfully by Allied aircraft, and was therefore abandoned in favour of expansion and improvement at Kornasoren. On 25 July, a USAAF Lockheed P-38 Lightning twin-engined fighter group was able to land there. By 2 September, a parallel pair of 7,000-ft (2135-m) runways had been completed, and soon after this Consolidated B-24 Liberator four-engined heavy bombers began operating from this airfield against Japanese petroleum facilities at Balikpapan in Borneo. Allied aircraft based on Noemfoor later played an important role in the battles of Sansapor and Morotai.

As far as the Japanese were concerned, the loss of Noemfoor made the 2^nd Area Army's position in the eastern part of the Vogelkop peninsula wholly untenable, and the army therefore pulled back the rest of Ikeda’s 35^th Division from Manokwari to Sorong at the extreme western end of New Guinea.

In combination, the 'Horlicks' and 'Cyclone' attacks on Biak and Noemfoor islands threatened to make a major dent in the Japanese strategic inner defence line, whose establishment had been ordered by Imperial General headquarters within the 'Kon' plan at the end of 1943, and running from the Mariana islands group south-west to the Palau islands then south to Biak island and west to the tip of New Guinea and finally south-west to Timor island.

Accordingly, Admiral Soemu Toyoda, commander-in-chief of the Combined Fleet since Admiral Mineichi Koga’s death in an air crash on 31 March 1944, detached Vice Admiral Matome Ugaki’s Mobile Force Vanguard (the super-battleships Yamato and Musashi, supported by older battleships, light aircraft carriers, cruisers and destroyers) from Vice Admiral Jisaburo Ozawa’s 1^st Mobile Fleet for the support of reinforcement operations for the garrisons of the 2^nd Area Army. But Ugaki’s force had only just reached Halmahera when it was recalled on 11 June to join the rest of the 1^st Mobile Fleet for 'A', so paving the way to the Battle of the Philippine Sea.

This powerful naval force could have made a considerable difference to the progress of MacArthur’s offensive in New Guinea, and its recall is striking evidence of Japan’s inability to cope with simultaneous offensives by the formations of the US Army and US Navy.