Which marine batallion, regiment defended the khe sahn combat base during the siege of 1968?

26th Marine Regiment -1st Battalion was on the east perimeter - Bravo Company was south of the runway and covered the main ammo dump - Alpha and Charlie Companies were on the north side of the runway. 3rd Battalions two companies were out on the west perimeter north of the special forces camp. 2nd Battalion was further west outside the perimeter on hill 558 and some of the other hills. If I remember correctly 12th and 13th Marine Artillery Regiments provided the music.