and RNZAF fighter squadrons left for Sumatra and Java at the beginning of February. It is not entirely clear how many Japanese aircraft the Buffalo squadrons shot down, although RAAF pilots alone managed to shoot down at least 20. Eighty were claimed in total, a ratio of kills to losses of just 1.3 to 1. Additionally, most of the Japanese aircraft shot down by the Buffalos were bombers. The Hawker Hurricane, which fought in Singapore alongside the Buffalo from 20 January, also suffered severe losses from ground attack; most were destroyed. Advance down the Malayan Peninsula The defeat of Allied troops at the Battle of Jitra by Japanese forces, supported by tanks moving south from Thailand on 11 December 1941 and the rapid advance of the Japanese inland from their Kota Bharu beachhead on the north-east coast of Malaya overwhelmed the northern defences. Without any real naval presence, the British were unable to challenge Japanese naval operations off the Malayan coast, which proved invaluable to the invaders. With virtually no remaining Allied planes, the Japanese also had mastery of the skies, leaving the Allied ground troops and civilian population exposed to air attack. The Malayan island of Penang was bombed daily by the Japanese from 8 December and abandoned on 17 December. Arms, boats, supplies and a working radio station were left in haste to the Japanese. The evacuation of Europeans from Penang, with local inhabitants being left to the mercy of the Japanese, caused much embarrassment for the British and alienated them from the local population. Historians judge that "the moral collapse of British rule in Southeast Asia came not at Singapore, but at Penang". However, many who were present during the evacuation did not experience it as a scramble. It was a response to an order from British High Command which had come to the conclusion that Penang should be abandoned as it had no tactical or strategic value in the rapidly changing military scheme of things at that time. On 23 December, Major-General David Murray-Lyon of the Indian 11th Infantry Division was removed from command to little effect. By the end of the first week in January, the entire northern region of Malaya had been lost to the Japanese. At the same time, Thailand officially signed a Treaty of Friendship with Imperial Japan, which completed the formation of their loose military alliance. Thailand was then allowed by