Following his attempted assault against the KMC regiment, the enemy opposite the 1st Marine Division reverted to a passive defense. Except for a probe late on 2 April of the far eastern line held by Lieutenant Colonel Pratt’s 3/1 and two patrols that scouted MLR positions in the western Korean Marine area that same date, Communist offensive measures consisted largely of artillery and mortar fire. Chinese line units appeared to concentrate on improving their dugouts and trench systems. Marines reported frequent sightings of enemy groups working in and around their forward trenches. Marine division troops, too, were busy fortifying their defensive positions. On the Kimpo Peninsula they dug gun emplacements and erected camp facilities for the newly activated Kimpo Provisional Regiment. North of the Han, mine clearance and construction of trenchworks and fortifications was the order of the day for most Marines. Other Marines patrolled forward of the lines as a major aspect of the division’s continuous active defense. During daylight hours, MLR regiments dispatched reconnaissance and combat patrols and sent out snipers, armed with telescope-equipped M-1 rifles. Division tanks firing from temporary gun slots on the main line and artillery batteries emplaced in rear area dugouts hammered away at enemy positions and disposed of his patrols. At night, harassing and interdicting (H&I) artillery fires and infantry raids continued to keep the Communists off-balance. A combat raid on 5 April typified the extensive Marine division night activities forward of the line. Conducted by three platoons, less a squad, of the KMC 10th Company, the raiding party had the mission of capturing prisoners. Departing the MLR at 2300, the Korean Marines worked their way over the low ground and then crossed the Sachon River. Immediately thereafter the raid leader, who was the 10th Company commander (First Lieutenant No Won Keun) dispatched two squad-sized ambushes along the patrol route. The raiders then continued northwest toward their objective, an area near the village of Tonggang-ni, a half mile beyond the river. When about 50 yards from its objective, the patrol ran into tactical wire and an enemy sentry, who alerted his unit by rifle fire. The KMC raiders opened up and called in pre-planned mortar and artillery support. The CCF defenders replied immediately with rifles and machine gun fire.