resisted by III Corps of the Indian Army and several British Army battalions. The Japanese quickly isolated individual Indian units defending the coastline, before concentrating their forces to surround the defenders and force their surrender. The Japanese forces held a slight advantage in numbers in northern Malaya and were significantly superior in close air support, armour, co-ordination, tactics, and experience, having fought in the Second Sino-Japanese War. The Allies had no tanks, which had put them at a severe disadvantage. The Japanese also used bicycle infantry and light tanks, which allowed swift movement of their forces overland through terrain covered with thick tropical rainforest, criss-crossed by native paths. Although the Japanese had not brought bicycles with them (to speed the disembarkation process), they knew from their intelligence that suitable machines were plentiful in Malaya and quickly confiscated what they needed from civilians and retailers. A replacement for Operation Matador, named Operation Krohcol by British Indian Army, was implemented on 8 December, but the troops were easily defeated by the Royal Thai Police and the Japanese 5th Division. Force Z of the Royal Navy (battleship , battlecruiser , and four destroyers, under the command of Admiral Sir Tom Phillips) had arrived right before the outbreak of hostilities. Japanese aircraft based in Indochina sank Prince of Wales and Repulse on 10 December, leaving the east coast of Malaya exposed, allowing the Japanese to continue their invasion. Air war Background As a lower-priority theatre, the Allies had comparatively few modern aircraft to challenge the Japanese. In addition the Allies did not consider Japanese aircraft a significant threat. In 1941 the Allies assumed that Japan would only have a few hundred poor quality outdated aircraft. The respected Janes All the World's Aircraft for 1941 indicated that the Japanese only had a cluster of dated foreign and indigenous aircraft. Japanese pilots were also underrated, considered unlikely to make particularly good pilots. Prior to the invasion on 8 December there were 75 Allied aircraft stationed in northern Malaya and 83 in Singapore. The only fighter squadron in northern Malaya was No 21 Squadron RAAF that was equipped with 12 Brewster Buffalos. The Japanese had at least 459 aircraft available. Japanese aircraft and units The Japanese Navy's 22nd Air Flotilla (22nd Kōkū-Sentai) with 110 aircraft and commanded by Vice Admiral Matsunaga Sadaichi operating out of three air bases near Saigon took part in the initial attacks on