During March, the defenders, on order of General Cushman, began to push out from the perimeter. On 8 March, the ARVN Rangers conducted a series of sweeps east of the runway. The first patrol made no contact but the next two became heavily engaged with an NVA force of unknown size. The Rangers attacked and poured into the enemy trenches, got eye-ball to eye-ball with "their brothers from the North" and killed 26. On the 24th, a patrol from Company A, 1/9, made contact with two NVA platoons which were dug in approximately 1,500 meters northwest of Lieutenant Colonel Mitchell's main perimeter. The Marines attacked the enemy emplacements and in a four-hour battle killed 31 North Vietnamese. During the fighting, a UH-1E helicopter of VMO-6 was shot down while supporting the Marines but the crewmen were rescued.[66] Friendly casualties were five killed, four medevaced, and two with minor wounds. The largest encounter, however, came on 30 March when Company B, 1/26, received a chance to settle an old score. The target area was the same complex, approximately 850 meters south of the perimeter, where the B/1/26 patrol had been ambushed on 25 February.(195) The attack had been planned by the battalion commander, Lieutenant Colonel Frederick J. McEwan (who relieved Lieutenant Colonel Wilkinson on 1 March) and his operations officer, Major Charles E. Davis III, with careful attention to every detail. In fact, the 1/26 staff had been working on this attack for a month. The sweep was also closely coordinated with the FSCC to ensure that the maximum supporting arms were available. To support Company B, Lieutenant Colonel Hennelly's staff worked out a variation of the defensive fire plan with nine batteries participating. Marine artillery (1/13) formed the primary box and rolling barrage while the Army 175mms and TPQ-10 controlled aircraft were responsible for the sides of the secondary box. The latter fell on the high ground adjacent to the objective which might influence the battle. The plan called for Captain Pipes to move his unit into the primary box and follow approximately 75 meters in trace of the rolling barrage. As the company advanced, the entire cylinder also advanced. Outside the primary box, the sides of the secondary would open and close over the terrain like a giant accordion. One extremely important factor was that the artillery fire would not necessarily alert the enemy of the impending attack because the same technique had been used so frequently in that area. The element of surprise still belonged to the Marines.