On 13 February, Bennett and other senior Australian officers advised Percival to surrender, in the interests of minimising civilian casualties. Percival refused but unsuccessfully sought authority to surrender from his superiors. The following day the remaining British Commonwealth units battled on. The Australians established a defensive perimeter to the north-west of the city centre around Tanglin Barracks, while preparations were made to mount a final stand. Meanwhile, civilian casualties mounted as civilians crowded into the area now held by the Allies and bombing and artillery attacks intensified. Civilian authorities began to fear that the water supply would soon give out. Japanese troops killed 200 staff and patients after they captured Alexandra Barracks Hospital.