sentences:  South of the Marines, on the high ground at Fire Support Base Lion (also called Nui Gio) was the 51st Regiment, 1st Division, with two of its battalions.General Diem's responsibility began southwest of his 51st Regiment, which was attached to Colonel Tri's command.The 3rd Infantry Regiment, with two battalions, held the high ground around Firebase Birmingham, above the Song Huu Trach, south of Huế.