side of Route 3 on the morning of 3 April. East of the road, the 24th Division moved astride the Yongp'yong River valley, the 5th Infantry Regiment on the left advancing into the Kwanum Mountain mass abutting Route 3, the 21st Infantry Regiment striking for Kungmang Mountain just inside the right Corps' boundary. West of Route 3, the 27th and 35th Infantry Regiments of the 25th Division advanced toward high ground rising between a lateral stretch of the Yongp'yong River and the Hantan River farther north. Pushing scattered People's Volunteer Army (PVA) 26th Army forces out of position by fire and occasionally by assault, and turning back a few light counterattacks, the 25th Division took the heights overlooking the Hantan River on 5 April. Resistance to the 24th Division was desultory except at the far right where the 2nd Battalion, 21st Infantry, stalled on the western slopes of Kungmang Mountain on 4 April, under fire from a strong PVA 40th Army force dug in on the crest behind barbed wire and antipersonnel mines. The battalion finally cleared the position after air strikes and artillery fire had softened it on the morning of 5 April. The 5th Infantry occupied the Kwanum Mountain mass that same day; slowed by the Kungmang battle, the 21st Infantry reached the Kansas Line on 6 April. The adjoining British 27th Brigade following the Kap'yong River valley on the IX Corps' left was stopped by PVA fire from Kungmang Mountain until the 21st Infantry reduced that position; then the British marched unopposed to the Kansas Line on 6 April. Flushing scattered PVA out of the IX Corps' central zone, the ROK 6th Infantry Division reached its Kansas objectives the same day. On the Corps' right, where the 1st Cavalry Division advanced astride the Pukhan River, the attached 7th Marine Regiment moved easily up the west side of the river, but the 7th and 8th Cavalry Regiments attacking through cut-up, virtually roadless ground east of the Pukhan were slowed by strong delaying forces of the PVA 39th Army. On 6 April the two cavalry regiments were still some short of their Kansas Line objectives adjacent to the Hwach'on Reservoir. Hwach'on Reservoir General Ridgway suspected that the stiff resistance to the 1st Cavalry Division was related to enemy plans to obstruct IX Corps' movement by releasing the reservoir's water through the Hwacheon Dam and flooding the Pukhan. The water