the Japanese to resume sovereignty over several sultanates in northern Malaya, thus consolidating their occupation. The 11th Indian Division managed to delay the Japanese advance at Kampar for a few days, in which the Japanese suffered severe casualties in terrain that did not allow them to use their tanks or their air superiority to defeat the British. The 11th Indian Division was forced to retreat when the Japanese landed troops by sea south of the Kampar position. The British retreated to prepared positions at Slim River. At the Battle of Slim River, in which two Indian brigades were practically annihilated, the Japanese used surprise and tanks to devastating effect in a risky night attack. The success of this attack forced Percival into replacing the 11th Indian Division with the 8th Australian Division., and cleared the route to the city of Kuala Lumpur. It did not take long for the Japanese army's next objective, the city of Kuala Lumpur, to fall. The Japanese entered and occupied the city unopposed on 11 January 1942. Singapore Island was now less than away for the invading Japanese army. Defence of Johor By mid-January, the Japanese had reached the southern Malayan state of Johore where, on 14 January, they encountered troops from the Australian 8th Division, commanded by Major-General Gordon Bennett, for the first time in the campaign. During engagements with the Australians, the Japanese experienced their first major tactical setback, due to the stubborn resistance put up by the Australians at Gemas. The battle—centred around the Gemencheh Bridge—proved costly for the Japanese, who suffered up to 600 casualties. However, the bridge itself (which had been demolished during the fighting) was repaired within six hours. As the Japanese attempted to outflank the Australians to the west of Gemas, one of the bloodiest battles of the campaign began on 15 January on the peninsula's West coast near the Muar River. Bennett allocated the 45th Indian Brigade—a new and half-trained formation—to defend the river's South bank but the unit was outflanked by Japanese units landing from the sea and the Brigade was effectively destroyed with its commander, Brigadier H. C. Duncan, and all three of his battalion commanders killed. Two Australian infantry battalions—which had been sent to support the 45th Brigade—were also outflanked and their retreat cut off, with one of the Australian battalion commanders killed in the fighting around the town of Bakri, south-east of Muar.