moving to Seremban in March. Further drafts of reinforcements arrived during this time as the battalion was brought up to its wartime establishment. The rigours of jungle training and the tropical heat affected the men, and a number of personnel were hospitalised during this time with illnesses such as malaria, measles, mumps and serious tropical skin diseases. Some of these were repatriated back to Australia, and by the end of March, the 2/18th was still below its authorised establishment, with an actual strength of 898. Amidst growing concerns amongst Australian military commanders about Japanese intentions, the scheduled replacement of the 22nd Brigade was cancelled, and the 2/18th remained in Seremban until they were transported east to Jemaluang in August. The following month they were sent north to Mersing, which, situated on the east coast of the Malay Peninsula, was considered a likely place for a Japanese landing as it offered a short route of advance towards Singapore. At Mersing, the battalion was set to work digging defensive positions and constructing wire obstacles, punctuated by familiarisation patrols and anti-aircraft, anti-gas and mortar training. The battalion was placed on a war footing on 6 December as tensions in the region escalated. Two days later, the Japanese invasion of Malaya commenced; while the fighting raged elsewhere, the 2/18th remained unengaged around Mersing. On 26 December, a small group of 2/18th men were detached to an ad hoc British raiding force known as "Roseforce" to take part in a raid behind Japanese lines, ambushing a Japanese convoy. It was not until 3 January however that the battalion came into contact with the Japanese for the first time, with a patrol from the 2/18th capturing two Japanese airmen who had been shot down near the mouth of the Sekakap River. A fortnight later, Japanese advances along the peninsula to the west led to concerns about the coastal defences being outflanked and cut off. As result, on 17 January, the 2/18th was ordered to withdraw south to Jemaluang without having met the Japanese in battle. Following a landing around Mersing, the Japanese began to advance south towards Jemaluang in large numbers. In response, on 26 January the 2/18th Battalion, supported by two batteries of artillery from the 2/10th Field Regiment, was tasked with establishing an ambush near the Nithsdale Estate and the rubber plantation at Joo Lye. Establishing themselves along the Mersing–Jemaluang road, 'D' Company was