[en]gaged in small patrolling actions and developed their own techniques of ferreting out enemy night patrols.
The Viet Cong quickly learned that the Capital Division was not an easy target for their guerrilla small-unit tactics. Within two months following the Capital Division's entrance into Vietnam, tactical units of the two regiments and the division initially deployed to Vietnam had reached a position nearly halfway between Qui Nhon and Muy Ba Mountain, nicknamed Phu Cat Mountain after the large town to the west of it. The people in that area had been dominated by the Viet Cong for many years. In the process of mopping up the small enemy pockets in the lowlands and rice paddies, military action caused many hardships for the local populace, making it so difficult for them to live that the women and children—and eventually all the pro-government segment of the population—gradually moved out of the area.
By June of 1966 the Capital Division controlled all the area north of Qui Nhon to the east of Highway 1 and up to the base of Phu Cat Mountain. It extended its control also to the north and south of Highway 19 up to the pass leading into An Khe. Working south along Highway 1 down toward Tuy Hoa and within the province of Binh Dinh, the Capital Division sent out reconnaissance parties and carried out small operations as far south as the border between Binh Dinh and Phu Yen.
The Korean Marine brigade, assigned at first to the Cam Ranh Bay Area in September and October 1965, was moved to the Tuy Hoa area in December of that year. The reason for the shift was the presence of the 95th Regiment near Tuy Hoa. This regiment, a North Vietnam divisional unit, had disappeared from the western area of South Vietnam and its whereabouts remained unknown for several weeks. It finally showed up in midsummer 1965 in the Tuy Hoa area where it began operations, threatening and dominating the outer regions of the Tuy Hoa area.
Tuy Hoa was a well-populated region, harvesting 60,000 to 70,000 tons of rice a year. The rice paddy land was poorly protected, wide open to control by the Viet Cong and North Vietnam's 95th Regiment. Since the Viet Cong and North Vietnamese utilized the area to supply rice to their own troops all the way up to the Central Highlands, the rice land had become a strategic necessity for the enemy. During the summer of 1965 the North Vietnamese 95th Regiment gained control of more and more of the rice production and by the middle of the wet season, October and November, a crisis had developed. The morale of
