area, while the communist U1 headquarters protected by Company 238, was situated on the plateau atop the Gang Toi Hills in an area which formed part of 1 RAR's objective. U1 was responsible for co-ordinating the Viet Cong regional defence against the Bien Hoa air base and for developing anti-government resistance and had been tasked with rebuilding the covert organisation in Bien Hoa city and the surrounding villages up to the Dong Nai, as well as re-establishing the link between Bien Hoa city and War Zone D, and for planning and executing attacks against the air base itself. Yet having relocated to the rainforest two months earlier, its presence was also unknown to the Australians and Americans. Regardless, A Company 1 RAR was scheduled to conduct a search of the plateau on the fourth day of the operation. Battle Insertion and patrolling, 5–7 November 1965 On 5 November 1 RAR began the routine search-and-destroy operation, inserting by helicopter south of the Song Dong Nai at 08:00, while the 1/503rd was inserted onto LZ King north-west of the Song Dong Nai and Song Be rivers at 11:00. The operation started badly for the Australians and Americans with the fly-in delayed. Despite a lengthy preparation by fire, a large Viet Cong force had been observed in the vicinity of LZ Queen prior to the insertion of the lead Australian rifle company—D Company under the command of Captain Peter Rothwell. The escorting helicopter gunships began taking small arms fire as they attempted to provide suppressing fire and Rothwell made the decision to activate the alternate landing zone to the north-east, LZ Princess. D Company was subsequently inserted safely and swept back to LZ Queen, securing it for the remainder of the battalion. By mid-morning 1 RAR occupied LZ Queen, with the 105 mm L5 pack howitzers of 105 Field Battery also flying-in to provide direct support. Augmenting the Australian gunners, the US 3/319 Artillery Battalion and 161st Battery, Royal New Zealand Artillery occupied FSB Ace further south. The scheme of manoeuvre adopted by 1 RAR dictated that each company undertake a dispersed patrol program in their own tactical area of responsibility, a fact which would allow them to search more ground, but limit their ability to concentrate combat power in the event of contact. A Company, under Major John Healy, patrolled east; B Company moved north along the Song Be to Xom Xoai,