Battle of Bong Son The Battle of Bồng Sơn was the second major battle for the US 1st Cavalry Division , an airmobile unit of divisional strength , during the Vietnam War . It also was called Operation Irving . A month earlier in 1965 , in the Battle of the Ia Drang , the 1st Cavalry used all the division infantry , but one brigade at a time . One of the realizations that affected Bong Son was that with adequate helicopter lift , the traditional need to keep a strong reserve was less required — the least involved unit usually could break away and go where it was needed . At the operational level , it was begun as a pursuit of the Vietnam People ' s Army ( PAVN ) 2nd , 18th , and 22nd Regiments ( forming the NVA 3rd Division ) by the Army of the Republic of Vietnam ( ARVN ) 22nd Division , commanded by Brigadier General Nguyen Thanh Sang and assisted by the Republic of Korea Capital Division . The NVA fought back strongly and Sang asked for reinforcements by two ARVN airborne battalions , which still were not enough . During the Battle of the Ia Drang , 1st Cavalry commander Major General Harry Kinnard had considered operations on the Binh Dinh plain , part of the area involved in Bong Son . He now had time to implement those ideas . Even through the ARVN needed help , the Cavalry prepared systematically . Preparation . Ia Drang demonstrated the fundamentally new capabilities , as well as the liabilities , of large , well - integrated airmobile forces , and Kinnard wanted to apply the lessons learned . It was planned as a divisional operation , rather than as the more reactive operations at Ia Drang in September and October 1965 . Rather than troop movement alone , the division staff dealt with psychological operations and civil action , not only protecting the 250 , 000 civilians , rice farms , and salt production in the area , but , with the controversial " hearts and minds " approach that Westmoreland tended to dismiss , extensive steps were taken to deal with both the enemy and the potential friends . Background . Binh Dinh province stretches from the mountains to the seacoast of Vietnam . It is full of contrasting terrain , and today is an important area of tourism in Vietnam . The same geography that makes it a tourist attaction made it a key transportation nexus during the Vietnam War , linking Nha Trang , Pleiku , Hội An , Da Nang and Huế , and providing access for the now - historic Ho Chi Minh Trail through Vietnam , Laos , and Cambodia . That the area had coast on the South China Sea allowed Naval fire support to be added to the three allied national forces . ARVN junks and the United States Navy ( USN ) sealed escape routes to the sea and provided fire support from the destroyers and , plus several smaller ships . Preliminaries . A local Viet Cong ( VC ) unit , the 2nd Regiment , had been reinforced by the 18th PAVN regiment ; they operated in a plain near the Dam Trao lake . Also in this are was the deep Kim Son and An Lao valleys . The Communist regiments had struck at Sang ' s command from the valleys , and were driving him back into defensive positions . Kinnard looked at the geography of the Bong Son plain , and saw the United States Army Special Forces camp and airstrip at Bong Son as a natural place to insert the 1st Cavalry , which could then move to any of four geographical areas . He knew that a pressed PAVN battalion or regiment would itself move if threatened , and counted on it doing so , planning to use " hammer and anvil " tactics to start the enemy moving , when they would be easier to detect , and to drive them into ambushes . Early movements by 1st Cavalry . Kinnard , now commanding the 3rd Brigade of the 1st Cavalry , secured Bong Son , and then probed at the enemy , opening his serious operations on 28 January . He had established base " Dog " , on high ground along Highway 1 . With as much stealth as possible , he moved part of his command into blocking positions at the north end of the plain . The plan was for Kinnard ' s forces in the valleys , along with ARVN units to " encourage " the Communists to fall back into the ambushes . Weather and having a howitzer - carrying helicopter shot down on 29 January , started the fight prematurely . The weather broke , however , and now that the enemy had been located by fighting with the fire bases , Moore ' s three battalions attacked the 22nd Regiment from three directions . As this four - day fight wound down , Kinnard moved the 2nd Brigade into the mountains at the An Lao valley , the 3rd Brigade at the south end , where they were covered by artillery . United States Marines pressured the enemy force in the valley , while Sang blocked the exits . This operation was of limited effect , as the enemy had moved into the jungle and mountains . A reinforced battalion made a night air assault on the beaches east of Hoa Hoi and moved into the encirclement , with illumination from an AC - 47 gunship , artillery , and the destroyer . The enemy was hit heavily by artillery fire from the cavalry ' s helicopter - lifted howitzers , and helicopters operated at night in fire support , supply , and medical evacuation roles . A B - 52 strike also was made on the suspected 2nd Regiment command post , with limited results , Pressure and pursuit . On 10 February , the 1st Brigade ( Archie R . Hyle , commanding ) flew from An Khe into the Kim Son valley , where Moore ' s brigade implemented an idea he had been planning since October . He flew an air assault onto the valley floor , only after company - size ambush forces were astride the exits of the valley . Contact was made with Communist forces on every one of the escape routes , and they took casualties both from the ambushing companies and the prepared artillery , the latter including heavy , long - range artillery moved by road into the area . A captured VC battalion commander talked enough about his unit for Kinnard to find the 2nd Regiment headquarters , in an area that became known as the " Iron Triangle " . 2nd Brigade ( Colonel Ray Lynch , commanding ) committed to this area , and fought a two - week battle , along with Moore ' s 3rd Brigade . Aftermath . After 41 days of fighting , the U . S . , ARVN , and South Korean forces had maneuvered in a complete circle around Bong Son , breaking up the 3rd NVA Division . Sang ' s ARVN division was able to move back in and take control of the plain . Hay observed that Bong Son involved new levels of complexity in planning and coordination . He described the ideal planning sequence being quite different than used by ground units : In the formal after - action report , it was observed that since good intelligence of VC unit locations is difficult to obtain , the force must be able to respond quickly to spot reports . A more deliberate approach recognizes that " the enemy will not generally stand and fight when faced by a superior force aggressively employed , preferring to fade away into the bush in classic guerrilla fashion . " To forestall this classic move , his escape must be predicted , and ambushes placed ; it is as important to block his escape routes as to directly attack his force .