Battle of Morotai
The Battle of Morotai, part of the Pacific War, began on 15 September 1944, and continued until the end of the war in August 1945. The fighting started when United States and Australian forces landed on the southwest corner of Morotai, a small island in the Netherlands East Indies, which the Allies needed as a base to support the liberation of the Philippines later that year. The invading forces greatly outnumbered the island's Japanese defenders and secured their objectives in two weeks. Japanese reinforcements landed on the island between September and November, but lacked the supplies needed to effectively attack the Allied defensive perimeter. Intermittent fighting continued until the end of the war, with the Japanese troops suffering heavy loss of life from disease and starvation.
Morotai's development into an Allied base began shortly after the landing, and two major airfields were ready for use in October. These and other base facilities played an important role in the Liberation of the Philippines during 1944 and 1945. Torpedo boats and aircraft based at Morotai also harassed Japanese positions in the NEI. The island's base facilities were further expanded in 1945 to support the Australian-led Borneo Campaign, and Morotai remained an important logistical hub and command center until the Dutch reestablished their colonial rule in the NEI.
Background
Morotai is a small island located in the Halmahera group of eastern Indonesia's Maluku Islands. Most of the island's interior is rugged and covered in thick jungle. The Doroeba Plain in Morotai's south-west corner is the largest of the island's few lowland areas. Prior to the outbreak of war, Morotai had a population of 9,000 and had not been commercially developed. It formed part of the Netherlands East Indies and was ruled by the Dutch through the Sultanate of Ternate. The Japanese occupied Morotai in early 1942 during the Netherlands East Indies campaign but did not garrison or develop it.In early 1944, Morotai became an area of importance to the Japanese military when it started developing the neighbouring larger island of Halmahera as a focal point for the defence of the southern approaches to the Philippines. In May 1944, the Imperial Japanese Army's 32nd Division arrived at Halmahera to defend the island and its nine airstrips. The division had suffered heavy losses when the Take Ichi convoy transporting it from China was attacked by American submarines. Two battalions from the 32nd Division's 211th Infantry Regiment were sent to Morotai to develop an airstrip on the Doroeba Plain. Both battalions were withdrawn to Halmahera in mid-July and the airstrip was abandoned because of drainage problems. Allied code breakers detected the Japanese buildup at Halmahera and Morotai's weak defenses, and passed this information on to the relevant planning staff.
In July 1944, General Douglas MacArthur, the commander of the South West Pacific Area, selected Morotai as the location for air bases and naval facilities needed to support the liberation of Mindanao in the Philippines. At the time this landing in the Philippines was planned for 15 November. While Morotai was undeveloped, it was preferred over Halmahera, as the larger and much better-defended island was judged too difficult to capture and secure. The occupation of Morotai was designated Operation Tradewind. The landing was scheduled to take place on 15 September 1944, the same day as the 1st Marine Division's landing at Peleliu. This schedule allowed the main body of the United States Pacific Fleet to simultaneously protect both operations from potential Japanese counter-attacks.
As little opposition was expected at Morotai, Allied planners decided to land the invasion force close to the airfield sites on the Doroeba Plain. Two beaches on the south-west coast of the island were selected as suitable landing sites and were designated Red Beach and White Beach. The Allied plan called for all three infantry regiments of the 31st Division to be landed across these beaches on 15 September and swiftly drive inland to secure the plain. As Morotai's interior had no military value, the Allies did not intend to advance beyond a perimeter needed to defend the airfields. Planning for the construction of airfields and other base installations was also conducted prior to the landing, and tentative locations for these facilities had been selected by 15 September.
Prelude
Opposing forces
At the time of the Allied landings, Morotai was defended by approximately 500 Japanese soldiers. The main unit was the 2nd Provisional Raiding Unit, which had gradually arrived on the island between 12 and 19 July 1944, to replace the 32nd Division's battalions when they were withdrawn. The 2nd Provisional Raiding Unit comprised four companies and was manned by Japanese officers and Formosan soldiers. Small elements of several other infantry, military police and support units were also present on the island. The 2nd Provisional Raiding Unit's commander, Major Takenobu Kawashima, deployed the unit in the south-west sector of the island and used the smaller units to establish lookout posts and detachments around Morotai's coastline. The largest of these outposts was on the island's north-east end at Cape Sopi, which consisted of about 100 men. The Japanese force was too small and widely dispersed to be able to mount an effective defense, so the 32nd Division ordered it to build dummy camps and use other deceptions in an attempt to trick the Allies into thinking that Morotai was strongly held.The Allied force assigned to Morotai outnumbered the island's defenders by more than one hundred to one. The Tradewind Task Force was established on 20 August under the command of Major General Charles P. Hall and numbered 40,105 U.S. Army soldiers and 16,915 United States Army Air Forces and Royal Australian Air Force personnel. The Tradewind Task Force came under the overall command of the United States Sixth Army; its main combat elements were the XI Corps headquarters, the 31st Infantry Division and the 126th Regimental Combat Team from the 32nd Infantry Division. These units were supported by engineers and a large anti-aircraft group. The Tradewind Task Force also included large numbers of construction and other line of communications units whose role was to swiftly develop the island into a major base. The 6th Infantry Division was designated the force reserve but remained on the mainland of New Guinea. MacArthur accompanied the force on board but was not in direct command of the operation.
The landing force was supported by powerful air and naval forces. The United States Fifth Air Force provided direct support while the Thirteenth Air Force and No. 10 Operational Group RAAF conducted strategic missions in the NEI and Philippines. The naval force was designated Task Force 77 and was organised into two attack groups, four reinforcement groups, a support group and an escort carrier group. The attack and reinforcement groups were responsible for transporting the assault force and subsequent support units and comprised twenty-four destroyers, four frigates, two Australian LSIs, five APDs, one LSD, twenty-four LCIs, forty-five LSTs, twenty LCTs and eleven LCIs armed with rockets. The support group was made up of two Australian heavy cruisers, three US light cruisers and eight US and two Australian destroyers. The escort carrier group comprised six escort carriers and ten destroyer escorts and provided anti-submarine and combat air patrol. Task Force 38.4 with two fleet carriers, two light aircraft carriers, one heavy cruiser, one light cruiser and thirteen destroyers was also available to support Task Force 77 if required.
Preliminary attacks
Preliminary air attacks to suppress the Japanese air forces in the vicinity of Morotai began in August 1944. At this time, the Allied intelligence services estimated that there were 582 Japanese aircraft within of Morotai, 400 of which were in the objective area. The Allied air forces conducted heavy raids on airfields in the Halmaheras, Celebes, Ceram, Ambon, Boeroe and other areas. US Navy carrier-borne aircraft also attacked Japanese air units based at Mindanao and mounted further attacks on Halmahera and Celebes. These attacks were successful, and by 14 September it was estimated that only 60 aircraft remained in the vicinity of Morotai.To preserve surprise, the Allies did not bombard Morotai prior to the invasion and conducted only a few photographic reconnaissance flights over the island. An Allied Intelligence Bureau patrol had been landed in the island in June but the information it collected was not passed on to the Sixth Army. Although the Tradewind Task Force had little information on the invasion beaches or Japanese positions, the Sixth Army did not land any of its reconnaissance patrols on Morotai, as it was feared that these could warn the island's defenders that an attack was imminent.
The Tradewind Task Force embarked onto the invasion convoy at several bases in north-west New Guinea, and conducted landing rehearsals at Aitape and Wakde Island in early September. The convoy gathered at Maffin Bay on 11 September and set out for Morotai the next day. Its voyage was uneventful, and the convoy arrived off Morotai on the morning of 15 September without having been detected by Japanese forces.
Allied landings
The battle of Morotai began at 6:30 on the morning of 15 September. Allied warships conducted a two-hour-long bombardment of the landing area to suppress any Japanese forces there. This bombardment set several villages on fire, but caused few Japanese casualties as they did not have many troops in the area.The first wave of American troops landed on Morotai at 8:30 and did not encounter any opposition. The 155th and 167th RCTs landed at Red Beach and the 124th RCT at White Beach. Once ashore, the assault troops assembled into their tactical units and rapidly advanced inland. By the end of the day the 31st Division had secured all of its D-Day objectives and held a perimeter inland. There was little fighting and casualties were very low on both sides. The Japanese 2nd Provisional Raiding Unit was unable to offer any resistance to the overwhelming Allied force, and withdrew inland in good order. Japanese 7th Air Division aircraft based at Ceram and Celebes began a series of nightly air raids on Morotai on 15 September, but these had little effect on the Allied force.
The lack of resistance was fortunate for the Allies due to unexpectedly poor beach conditions. While the limited pre-invasion intelligence suggested that Red and White beaches were capable of supporting an amphibious landing, they were in fact highly unsuitable for this purpose. Both beaches were muddy and difficult for landing craft to approach owing to rocky ridges and coral reefs. As a result, soldiers and equipment had to be landed through deep surf. This delayed the operation and caused a large quantity of equipment to be damaged. Like many of his soldiers, MacArthur was forced to wade through chest-high surf when he came ashore. On the morning of D-Day a survey party determined that a beach on the south coast of Morotai was much better suited to LSTs. This beach, which was designated Blue Beach, became the primary Allied landing point from 16 September.
The 31st Division continued its advance inland on 16 September. The division met little opposition and secured the planned perimeter line around the airfield area that afternoon. From 17 September, the 126th Infantry Regiment landed at several points on Morotai's coastline and offshore islands to establish radar stations and observation posts. These operations were generally unopposed, though patrols landed in northern Morotai made numerous contacts with small Japanese parties. The 2nd Provisional Raiding Unit attempted to infiltrate the Allied positions on the night of 18 September but was not successful.
A detachment from the Netherlands Indies Civil Administration was responsible for civil affairs on Morotai. This detachment came ashore on 15 September, and reestablished Dutch sovereignty over Morotai's civilian population. Many local civilians subsequently provided NICA with intelligence on Japanese dispositions on Morotai and Halmahera and others acted as guides for American patrols.
On 20 September, the 31st Division advanced further inland to secure an expanded perimeter. This was necessary to provide room for additional bivouacs and supply installations after General MacArthur's headquarters decided to expand airfield construction on the island. The advance met little resistance and was completed in one day. On 22 September, a Japanese force attacked the headquarters of the 1st Battalion, 167th Infantry Regiment but was easily repulsed. The following day, a company from the 126th Infantry Regiment unsuccessfully attacked a fortified Japanese unit near Wajaboeta on the island's west coast. The 126th resumed its attack on 24 September and secured the position. US forces continued intensive patrolling until 4 October when the island was declared secure. U.S. casualties during the initial occupation of Morotai numbered 30 dead, 85 wounded, and one missing. Japanese casualties were much higher, numbering over 300 dead and 13 captured.
The American ground troops did not require the heavy air support available to them, and the fast carrier group was released for other duties on 17 September. The six escort carriers remained in support, but their aircraft saw little action. Four of the CVEs were released on 25 September, and the remaining two departed on 4 October. The destroyer escort was sunk by Japanese submarine Ro-41 on 3 October while escorting the CVE group. Several hours later a TBF Avenger from the escort carrier USS Midway attacked north of where Shelton had been torpedoed, in the mistaken belief that she was the submarine responsible. After dropping two bombs, the TBF Avenger guided to the area and the destroyer escort sank Seawolf after five attempts, killing all the submarine's crew. It was later determined that while Seawolf was traveling in a designated "submarine safety lane", the CVE pilots had not been properly briefed on the lane's existence and location, and that the submarine's position had not been provided to USS Richard M. Rowell.
The U.S. Navy established a PT boat base at Morotai on 16 September when the tenders and arrived with motor torpedo boat squadrons 9, 10, 18 and 33 and their 41 boats. The PT boats' primary mission was to prevent the Japanese from moving troops from Halmahera to Morotai by establishing a blockade of the -wide strait between the two islands.
Elements of the 31st Division embarked from Morotai in November to capture several islands off New Guinea from which Japanese outposts could observe Allied movements. On 15 November 1,200 troops from the 2nd Battalion, 167th Infantry Regiment and attached units were landed at Pegun Island in the Mapia islands; the next day, Bras Island was attacked. The Mapia Islands were declared secure on 18 November after resistance from 172 Japanese troops of the 36th Infantry Division was overcome. On 19 November, a force of 400 US troops built around F Company, 124th Infantry Regiment occupied the undefended Asia Islands. These were the first offensive operations overseen by the Eighth United States Army, and the naval commander for both operations was Captain Lord Ashbourne of the Royal Navy on board. Radar and LORAN stations were subsequently established on the islands.