Operation Appease, or the battle of Talasea (6-16 March 1944) was the last major US advance on New Britain, and saw the US Marines capture Talasea, on the Willaumez Peninsula, cutting off the main route being used by Japanese troops attempting to flee from the western part of the island.
On 10 February General Kreuger announced that Operation Dexterity, the conquest of the western tip of New Guinea, was over. The Allied effort now switched to an advance east across the north coast to the Willaumez Peninsula. This narrow peninsula jutted north from the coast for about forty miles. The main target was Talasea, about half way up the east coast.
The first step towards Talasea was an amphibious attack on Iboki Peninsula, about half way between Cape Gloucester and Talasea. This was hit by fifty B-24s on 21 February and forty-two B-25s on 22 February, and the Marines then made an unopposed landing on 25 February.
The next step was the attack on Talasea. The plan called for a preliminary air bombardment by RAAF aircraft from Kiriwina, but poor weather at their base prevented them from taking off. Fighter support was provided by the US 80th Fighter Squadron, which had already moved onto the new airfield at Cape Gloucester.
The target area was defended by 430 Japanese troops from the 1st Battalion, 54th Infantry, commanded by Captain Kiyomatsu Terunuma. Until very recently the area had been a key Japanese staging post on the retreat back to Rabaul, but most of the troops had been withdrawn a few days before the attack. Most of the remaining Japanese were at Talasea, with a rifle platoon and a machine gun squad at Volupai.
The attack was carried out by the 5th Marines. Lacking the expected air support they had to improvise a bombardment, using their own tanks firing from the landing craft. One Piper Cub spotter plane was also available.
The 1st Battalion, 5th Marines, landed at Volupai Plantation, on the western shore of the Willaumez Peninsula, early on 6 March. The landing was delayed while the Marines waited for the expected air attack, but began at just before 8.30am. They were carried to shore on a flotilla of LVTs, capable of passing straight over the coral reefs off shore. The only resistance came from scattered rifle fire and some mortar fire.
They were followed by the 2nd Battalion, which ran into a Japanese defensive position on the edge of a coconut plantation. A combination of tanks and infantry eliminated this position and the advance continued.
On the night of 6-7 March the Japanese moved a new company to defend the track between the east and west coasts. The advancing marines ran into this line soon after dawn on 7 March, but by the time they attacked the Japanese had retreated. More serious resistance was encountered near Mt Schleuther, on the east coast, where the Japanese attempted to cut off the Marine advance guard. The Marines moved first, and defeated this attack, and ended the day in possession of Mt Schleuther.
Talasea airfield was captured on 8 March, after the Japanese withdrew to a position overlooking Bitokara village. This time the Japanese stood and fought, and the first American attack was repulsed. Once again the Japanese withdrew overnight. On 9 March the Marines focused on securing their objectives in the area, and confirming that the Japanese had indeed retreated. The main part of the battle had only last four days, and had cost the Marines 17 dead and 114 wounded.
Over the next few days the Japanese fought a series of delaying actions, intended to win time for their main force to complete its retreat from the western part of the island. The last of these clashes came on 16 March, and after that the Japanese concentrated on their retreat.
At the end of April the Marines were relieved by the US 40th Division. Their 185th Infantry captured Hoskins Plantation further east along the coast on 7 May. The campaign then settled down into a pattern of regular patrols and limited contact with the Japanese.