sentences:  Colonel Tri's outposts were just inside the Thua Thien-Quang Tri boundary, nearly 30km northwest of Huế.Here, under the direct command of the 14th Ranger Group, were the 77th Ranger Battalion, seven RF battalions, and a troop of armored personnel carriers of the 17th Armored Cavalry Squadron.The four Marine battalions of the 147th Brigade were in the vital Bo Corridor, within light artillery range of the Citadel, while the 78th and 79th Ranger Battalions were on outposts 10km west of the Marines.