Manggar airfield, on the eastern coast of Dutch Borneo, approximately 18 kilometres north east of Balikpapan, was the scene of the 2/14th Battalion's last major engagement of the Second World War. Manggar, with its two landing strips, was the largest airfield In the Balikpapan area and was thus a major objective for the landings. It also marked the easterly limit of landing force's advance - believing the operation to be strategically questionable Australian planners had limited its objectives to those critical to the security of the port and oil infrastructure at Balikpapan.
The 2/14th began is advance from the Balikpapan beachhead on 2 July and on the same day captured the smaller airfield at Sepinggang without difficulty. It continued towards Manggar the next day, dealing with several pockets of resistance en route, and finally arrived at the airfield on the morning of 4 July. Initially, it appeared undefended and the 2/14th's leading company was able to advance over a kilometre along its length. The Japanese, however, were well entrenched in the hills overlooking the airfield. There were two 6-inch coastal guns north of the airfield on a hill Waites Knoll, which was dominated by another higher feature known as Frost. Two spur lines, Brown and Green, descended south-east from Frost and upon these were sited several Japanese machine guns and artillery pieces. When they opened fire it came as a considerable shock to the 2/14th. Two explanations have been offered for the Japanese's delay in engaging the Australians. The first is that the speed of the 2/14th's advance had caught the Japanese offguard, while the other is that the Japanese were waiting for large numbers of Australians to begin crossing the open expanse of the airfield before opening fire.
Not willing to 'waste men's lives needlessly' the 2/14th's CO, Lieutenant Philip Rhoden, had the Japanese positions bombarded with artillery and naval gunfire for two days, before ordering an attack on the afternoon of the 6 July. The power of this bombardment was clearly demonstrated when a 13 man patrol was able to seize the heavily fortified coastal guns on Waites Knoll. This small force was quickly reinforced in order to fend off the inevitable counter attacks that ensued for two days. In the meantime, the other Japanese positions on Frost and Brown Spur were heavily bombarded. On the afternoon of 9 July, with little fire still coming from these positions, fighting patrols were dispatched to assault them; that directed against Brown Spur was supported by three tanks. All of the positions were captured with little resistance, thereby securing Manggar Airfield. In the course of the battle over 500 rounds of naval gunfire and 12,000 rounds of artillery ammunition had been expended.