In November 1941, after the 3rd and 17th PS received new P-40E aircraft, most of their P-35As were passed to two newly arrived squadrons attached to the group, the 21st and 34th PS, with the latter receiving most. The 21st PS received its P-40Es on the eve of war and transferred its few P-35s to the 34th Pursuit Squadron, which then had nearly a full squadron. It then fought with them in the futile defense of the islands in December 1941, initially at Del Carmen Airfield. They were hopelessly outclassed by the Japanese fighters. Lack of armor and self-sealing fuel tanks made the aircraft extremely vulnerable (12 P-35As were destroyed and six damaged by a Japanese strafing attack on Del Carmen Airfield on 10 December) and by 12 December 1941, only eight P-35As were still in flying condition. However, also on 10 December 1941, a P-35A of the 34th Pursuit Squadron piloted by 1st Lt. Samuel H. Marrett is credited with the sinking of Japanese minesweeper W-10 during the Japanese invasion of Vigan in northern Luzon. Marrett made multiple strafing runs against "W-10", until the ship blew up. The explosion was so powerful it tore a wing off of Marrett's P-35, causing him to crash into the sea.