The Kim Son Valley consisted of seven small river valleys about southwest of Bong Son. Three American battalions were deployed to the valley. On 11 February the 1st Cavalry established ambush positions in the highlands at the exits to each of the valleys and on 12 February began a sweep up the valley and outward, hoping to catch the PAVN/VC as they retreated. Initially unsuccessful, over the next few days the number of enemy dead slowly mounted as the result of over a dozen clashes with the Americans. On the morning of 15 February a platoon from Company B, 2/7th Cavalry, came under small-arms and mortar fire while patrolling about 4 km southeast of Firebase Bird, near the valley center. Captain Diduryk, the company commander, initially estimated that the opposing force was no larger than a reinforced platoon, but it soon became apparent that he had bumped into at least two companies occupying a 300m long position running along a jungled streambank and up a hillside. Intelligence later identified the force as part of the VC 93rd Battalion, 2nd Regiment. Fire from Company B's mortar platoon, from helicopter gunships and Skyraiders, and from artillery at Firebase Bird pounded the PAVN, then Diduryk's men attacked. One platoon fixed bayonets and charged the dug-in defenders across the stream. A second pushed north to block an escape route, and a third stayed in reserve. Unnerved by the frontal assault, the VC retreated in disorder. Many stumbled into the open and were quickly killed. Those who survived fled to the north, where they came within range of the waiting platoon. A smaller group attempted to escape southward but came under fire from the reserve platoon, which took many prisoners, including 93rd Battalion commander Lt. Col. Dong Doan who inadvertently provided his interrogators with enough information to identify the locations of both his regiment and its headquarters. During the fight Company B killed 59 VC and possibly another 90 for the loss of 2 killed.