Hurricanes were withdrawn to Sumatra. A squadron of Hurricane fighters took to the skies on 9 February but was then withdrawn to the Netherlands East Indies and after that no Commonwealth aircraft were seen again over Singapore; the Japanese had achieved air supremacy. That evening, three Fairmile B motor launches attacked and sank several Japanese landing craft in the Johor Strait around its western channel on the evening of 9 February. On the evening of 10 February, General Archibald Wavell, commander of ABDA, ordered the transfer of all remaining Commonwealth air force personnel to the Dutch East Indies. By this time, Kallang Airfield was, according to author Frank Owen, "so pitted with bomb craters that it was no longer usable". Second day Believing that further landings would occur in the northeast, Percival did not reinforce the 22nd Brigade until the morning of 9 February, sending two half-strength battalions from the 12th Indian Infantry Brigade. The Indians reached Bennett around noon. Shortly afterwards Percival allocated the composite 6th/15th Indian Infantry Brigade to reinforce the Australians from their position around the Singapore racecourse. Throughout the day, the 44th Indian Infantry Brigade, still holding its position on the coast, began to feel pressure on its exposed flank and after discussions between Percival and Bennett, it was decided that they would have to retire eastwards to maintain the southern part of the Commonwealth line. Bennett decided to form a secondary defensive line, known as the "Kranji-Jurong Switch Line" facing west between the two rivers, with its centre around Bulim, east of Tengah Airfield—which subsequently came under Japanese control—and just north of Jurong. To the north, the 27th Australian Brigade had not been engaged during the Japanese assaults on the first day. Possessing only the 2/26th and 2/30th, following the transfer of the 2/29th Battalion to the 22nd Brigade, Maxwell sought to reorganise his force to deal with the threat posed to the western flank. Late on 9 February, the Imperial Guards began assaulting the positions held by the 27th Brigade, concentrating on those held by the 2/26th Battalion. During the initial assault, the Japanese suffered severe casualties from Australian mortars and machine-guns and from burning oil which had been sluiced into the water following the demolition of several oil tanks by the Australians. Some of the Guards reached the shore and maintained a tenuous beachhead; at the height of the assault, it is reported