During the Vietnam War, the district of Phước Long played an important role in the defensive posture of the ARVN. Phước Long is about 120 km north of Saigon; it shared a border with the South Vietnamese districts of Bình Long in the west, Quảng Đức in the east, and Long Khánh District in the south. Phước Long also shares an international border with Cambodia. The district of Phước Long and the military zones of Bố Đức, Đôn Luân, Đức Phong, the administrative centre of Phước Bình, and Bà Rá mountain lay at the centre of South Vietnam's defensive line in III Corps, which served to defend Saigon and the populous southern provinces.