While the 1st and 3rd Brigades were patrolling the Kim Son Valley between 11 and 27 February, Colonel William R. Lynch's 2nd Brigade closed down operations north of the Lai Giang and transferred his command post to Landing Zone Pony just east of the valley. The move was triggered by Colonel Doan's revelation that the 2nd Regiment was operating in the mountains southeast of Pony, information that seemed to be confirmed when radio intercepts indicated the presence of a major PAVN/VC headquarters there. On 16 February Lynch began a block and sweep of the suspected terrain. Lt Col. Meyer's 2nd Battalion, 5th Cavalry Regiment, set up three blocking positions: Recoil, roughly 6 km east of the Kim Son Valley; Joe, 4 km southwest of Recoil; and Mike, just over 2 km north of Recoil. The sweep force, 1/5th Cavalry, plus a battery of the 1st Battalion, 77th Artillery Regiment, helicoptered to Landing Zone Coil approximately 6 km northeast of Recoil. 2/12th Cavalry remained near Pony as a reserve. At 06:30, on 17 February, the battery at Coil began pounding the area between Coil and Recoil. As the barrage lifted, two companies of 1/5th Cavalry moved off towards the three blocking positions. One of the companies moved out to establish a fourth blocking position east of Recoil, but before the men had gone more than a kilometer they were engulfed by fire from upslope. After calling in air strikes and artillery, Meyer directed one of his rifle companies to reinforce, but on its way it became so heavily engaged that it could not advance. Meyer then committed his third rifle company, and Colonel Lynch ordered 2/12th Cavalry to send a company as well. In the end, the cumulative weight of the American ground attack and the artillery and air strikes drove the VC from the heights, killing at least 127 VC and captured and destroyed 3 mortars, 5 recoilless rifles, and a quantity of ammunition, leading Lynch to conclude that he had crushed the 2nd Regiment's heavy weapons battalion.