The battle of Morotai (15 September - 4 October 1944) was carried out in order to protect the left flank of any American advance from New Guinea to the southern Philippines, and took them into the Molucca Islands.
Morotai is part of the Halmahera Group, the northernmost of the Moluccas. An airbase on Morotai could be used to support the planned attack on Mindanao, and also to guard the left-flank of the allied advance against Japanese aircraft from the Celebes in the west and Ambon in the south.
The Japanese were believed to have 30,000 men on Halmahera and another 1,000 on Morotai. True to form MacArthur decided to attack the weaker of the two and use it as a base to isolate the larger force. This emphasis can be seen in the composition of the Tradewind Task Force, the army allocated to the invasion. Of the 61,000 men involved in the attack, about one third were front line troops, while the rest were there to build a new Allied base.
Morotai is an oval shaped island about 40 miles from north to south and 25 from west to east. The interior was mountainous, and covered with rain forests. The biggest area of flat ground was the Doroeba plain in the south-west of the island. To the south of this area was the long narrow Pila Peninsula, which extended south from the mainland. The area to the east of the peninsula is Potoe Bay. The Japanese had a small garrison on the island, 500 men from the 2nd Raiding Unit. They had begun work on an airfield, but soon abandoned it. They had around 11,000 combat troops on Halmahera, and intended to use them to expel any American force that landed on Morotai, ignoring the difficulties of moving any troops across a sea passage dominated by Allied aircraft and PT boats.
The attack was to be carried out by Alamo Force. A fifteen mile perimeter was to be established, and airfields built within in. The 31st Division and the 126th Regimental Combat Team of the 32nd Division, were chosen to carry out the attack. The 31st Division was to carry out the main attack and the 126th RCT to act as the reserve. This gave the attacking force around 28,000 combat troops, along with just over 40,000 support troops.
The attack was to be supported by three task forces from the Seventh Fleet and one from the main Pacific Fleet. The amphibious force had twelve destroyers, five destroyer transports and over sixty transport ships (a mix of LCIs, LSTs and LCTs). The Close Support and Covering Force had two heavy cruisers, three light cruisers and ten destroyers. Finally Admiral Thomas L. Sprague commanded the air support group (TF 78), made up of six escort carrier and ten destroyers. The Third Fleet provided a fast carrier group, with two fleet carriers, two light carriers, three heavy cruisers and twelve destroyers, under Vice Admiral John S. McCain. Land based air support was provided by the Fifth Air Force, operating from its bases along New Guinea.
The landings were to be carried out on the western side of the Gila Peninsula, so that the support troops could quickly begin work on the airfields on the flat area just to the north. Two beaches were chosen - White Beach about half way up the peninsula, and Red Beach, just beyond its northern tip.
The 124th Infantry from the 31st Division was to land on White Beach and split in two, with one battalion heading south to secure the rest of the peninsula and one heading north-east to take the northern coast of Potoe Bay.
The 167th Infantry, 31st Division, was to land on the southern half of Red Beach. Two battalions were then to advance east and take the Japanese airfield while the rest formed a reserve.
The 115th Infantry, 31st Division, was to land on the northern half of Red Beach and advance to the north of the airfield.
In the two weeks before the invasion Allied aircraft had avoided Morotai, but they had repeatedly attacked every Japanese airfield within range. On D-Day itself the fast carrier force attacked the Celebes while other aircraft hit nearer airfields and bombardment Morotai. The main effort was made against nearby Halmahera, which was also the target of a naval bombardment.
The invasion was preceded by a bombardment by elements of the Seventh Fleet, which began two hours before H-Hour. The landings themselves went in on time. Troops reached Red Beach exactly on time at 8.30am, while coral reefs just off shore delayed the landings on White Beach by one minute. There was no Japanese resistance at either beach. This was fortunate, as the beaches turned out to be very unpleasant terrain - Red Beach was judged to be the worst in the entire Southwest Pacific campaign, and was made up largely of thick mud. The difficult conditions caused great problems for the landing craft. By the end of the day Red Beach was judged to be unusable, and further south a 'New White Beach' had to be adopted. Much better beaches were soon found on the eastern shore of the peninsula, and from D+1 all LSTs and most other landing craft used this new Blue Beach.
Once the Americans were past the beaches themselves things got much easier. The terrain was well drained and fairly level, and the all four attacking units easily achieved their D-Day objectives. Only the 124th Infantry came into contact with the Japanese, losing 7 wounded by the end of the day. Twelve Japanese troops were killed and one captured.
Within two hours MacArthur came ashore in person. He was reported to have stared towards the Philippines, and said 'They are waiting for me there. It has been a long time'.
On 16 September the Americans extended their beachhead until it was 7,000 yards wide from east to west and 5,000 yards from north to south. Japanese resistance was still very limited. An extended perimeter was established by 20 September, and work began on a more ambitious airfield construction programme.
There was very little fighting on Morotai. American patrols sometimes ran into isolated Japanese groups, but they almost always fled the moment they were attacked. On4 October General Krueger officially announced that the campaign was over. By that point the Americans had lost 30 dead, 85 wounded and 1 missing, and reported 104 Japanese dead and 13 prisoners. Another 200 Japanese troops may have been killed when their barges were sunk on the route between Morotai and Halmahera.
Work on the airfields advanced at some speed. The original Japanese airfield at Pitoe turned out to only be suitable for fighters, and it was ready for use on 29 September. The first bomber field was built near Gotalalamo village, and was called Wama Drome. The first 4,000ft of runway were ready by 4 October, and it eventually reached 5,000ft. Work on a third airfield, Pitoe Drome, began on 23 September and it was ready for the first aircraft by 17 October. This was much slower than expected in the original plans, but still an impressive achievement on very difficult terrain. Fighters based on Morotai began to provide bomber escorts on 7 October and B-25 operations began on 13 October. Eventually these airfields played a major part in neutralising Japanese air power in large parts of the Dutch East Indies.