Artillery fired for more than two hours on the morning of 6 June to soften defenses on the next regimental objective, Hill 729. An air strike was attempted but fog with low-hanging clouds forced the flight leader to abort the mission. At 1300 the assault battalions moved across the LD against small-arms and machine gun fire. The fog lifted sufficiently at 1400 to allow four F9Fs from VMF-311 to deliver an effective attack. And by 2100 both 2/5 and 3/5 were consolidating their positions on the first of the five ridges. This assault is typical of the fighting as the 5th Marines took the remaining four ridges, one by one, in a slugging assault on an enemy defending every commanding height. The advance resolved itself into a pattern as the Korean Reds probed the Marine lines at night and continued their tough resistance by day. For 10 days the regiment plugged ahead, step by step, with the support of artillery, air, mortars, and 75 mm recoilless rifles.[235] [235] _HD_s of 1stMarDiv and 1stMar, Jun 51. _1st Marines Moves Up to_ BROWN _Line_ On the left flank, the 1st Marines devoted several days to consolidating its position and sending out reconnaissance patrols in preparation for an attack on the ridge just north of the Hwachon Reservoir. From this height the Communists could look down the throats of Colonel Brown’s troops. From 6 to 8 June, Lieutenant Colonel Hire’s 3d Battalion led the attack against moderate but gathering resistance. A gain of 1,500 yards was made on the right flank by 2/1, commanded by Major Clarence J. Mabry after the evacuation of Lieutenant Colonel McClellan, wounded on the 5th. On the left, Lieutenant Colonel Robley E. West’s 1/1 held fast as the 5th ROK Regiment, 7th ROK Division, X Corps, passed through on its way to a new zone of action to the west. Early on the 9th, as 2/1 was preparing to launch its attack, an intense artillery and mortar barrage fell upon the lines, followed by the assault of an estimated NKPA company, The Korean Reds were beaten off with heavy losses. And though the enemy fire continued, 2/1 jumped off on schedule, fighting for every inch of ground. Colonel Brown committed 1/1 on the left. It was an all-day fight for both battalions. After taking one ridge in the morning, it was used as the springboard for an assault on the second objective. The weapons of the regimental Anti-Tank Company built up a base of fire that enabled this ridge to be secured by 1600. The 5th ROK Regiment took its objectives by the morning of the 10th. The 1st Marines provided additional fire support by diverting all its antitank guns and tank rifles to the aid of the ROKs.