Porter expected that fighting for the main objectives would begin soon after the landing, and decided to begin landing his artillery and heavy mortars with the assault waves of infantrymen, just before the tanks came ashore. The 2/28th Battalion was initially assigned responsibility for securing Victoria and Flagstaff Hill to its north, while the 2/43rd Battalion was tasked with capturing the airfield. Once these areas were in Australian hands, the 2/28th Battalion would secure the western part of the island while the 2/11th Commando Squadron captured the western shore of Victoria Harbour. Due to the Australian Army's manpower shortages, all elements of the 9th Division were under orders to minimise their casualties during the Borneo Campaign and unit commanders would rely heavily upon the available air and artillery support during operations. The Australians estimated that the Japanese garrison on Labuan comprised 650 personnel, made up of 400 airfield troops, 100 naval troops and 150 other lines-of-communications personnel.