and ambushes were initially conducted out to Line Alpha (), which was the range of the Viet Cong (VC) mortars, but were later extended out to Line Bravo () to counter the threat from artillery. All inhabitants of Long Phước and Long Hải villages within Line Alpha were removed, and resettled nearby. A protective security zone was established and a free-fire zone declared. Although unusual for allied installations in Vietnam, many of which were located near populated areas, the Australians hoped to deny the VC observation of Nui Dat, and afford greater security to patrols entering and exiting the area. While adding to the physical security of the base through disrupting a major VC support area and removing the local population from danger, such measures may have been counter-productive. The resettlement resulted in widespread resentment. The VC continued to observe the base from the Nui Dinh hills. Movement was heard around the perimeter over the first few nights as they attempted to locate the Australian defences under the cover of darkness and heavy rain. Although no clashes occurred and the reconnaissance soon ceased, they were believed to be preparations for an attack. On 10 June reports indicated that a VC regiment was moving towards Nui Dat from the north west and was about away. The same day three 120 mm mortar rounds landed just outside the base. That night Australian artillery fired on suspected movement along Route 2, but no casualties were found the next day. Further warnings of an attack hastened the call-forward of 6th Battalion, Royal Australian Regiment (6 RAR), which arrived from Vũng Tàu to the south on 14 June. No attack occurred, and the initial reaction to 1 ATF's lodgement proved unexpectedly limited. Opposing forces Communist forces The principal communist units in Phước Tuy were main forces from the 274th and 275th Regiments of the VC 5th Division. Under command of Senior Colonel Nguyen The Truyen, the division was headquartered in the Mây Tào Mountains. Operating in Phước Tuy, Biên Hòa and Long Khánh Provinces, it comprised both South Vietnamese VC guerrillas and North Vietnamese People's Army of Vietnam (PAVN) units. Given the task of isolating the eastern provinces from Saigon by interdicting the main roads and highways, including National Routes 1 and 15 and provincial routes 2 and 23, it proved a major challenge to Army of the Republic of Vietnam (ARVN) units that ventured