Continued Japanese dominance eventually forced both Squadrons back to Singapore on 24 December, where they were merged until more replacement aircraft could be obtained. No 64 Squadron had run out of aircraft and its surviving ground-crew and airmen were shipped to Burma. RAAF No 1 and No 8 squadrons were amalgamated due to aircraft losses. This left the Allied ground troops and shipping completely open to air attack and further weakened the defensive position. The Genzan Air Group sank "Prince of Wales" and "Repulse" on 10 December, which also established Japanese naval supremacy. In comparison, the Japanese army enjoyed close air support from the start of the campaign, and sought to capture bases for their air support to operate from.