The 2nd Squadron reached the peninsula's base at 2:30 pm, where it began to prepare its main line of resistance (MLR). By the end of 15 December, more than 1,600 Allied troops were ashore. The two Japanese Army companies that had been stationed at Arawe withdrew to the northeast, and took up positions at Didmop on the Pulie River about from the MLR; the naval unit defending Umtingalu retreated inland in a state of disarray. The Allied naval force off Arawe was subjected to a heavy air raid shortly after the landing. At 9:00 am, eight Aichi D3A "Val" dive bombers escorted by 56 A6M5 "Zero" fighters evaded the USAAF combat air patrol (CAP) of 16 P-38 Lightnings. The Japanese force attacked the recently arrived first supply echelon, which comprised five Landing Craft Tank (LCT) and 14 Landing Craft Medium (LCM), but these ships managed to evade the bombs dropped on them. The first wave of attackers suffered no losses, but at 11:15 am four P-38s shot down a Zero, and at 6:00 pm a force of 30 Zeros and 12 Mitsubishi G4M3 "Betty" and Mitsubishi Ki-21-II "Sally" bombers was driven off by four P-38s. The Japanese lost two Zeros in the day's air actions, but both pilots survived. Although the U.S. ground troops faced no opposition in the days immediately after the landing, naval convoys carrying reinforcements to the Arawe area were repeatedly attacked. The second supply echelon came under continuous air attack on 16 December, resulting in the loss of as well as damage to , and four LCTs. About 42 men on board these ships were killed or seriously wounded. Another reinforcement convoy was attacked three times by dive bombers on 21 December as it unloaded at Arawe. Overall, at least 150 Japanese aircraft attacked Arawe that day. Further air attacks took place on 26, 27 and 31 December. However, the Allied air forces were able to mount a successful defense of the Arawe area as the coastwatcher parties in New Britain provided 30 to 60 minutes warning of most incoming raids. Between 15 and 31 December, at least 24 Japanese bombers and 32 fighters were shot down near Arawe. During the same time period, Allied air units also raided airfields at Rabaul and Madang in New Guinea which were believed to be the bases of the aircraft which had attacked Arawe.