The Battle of Bong Son was fought between the US 1st Cavalry Division and North Vietnamese Army units, from January 28 to February 12, 1966, during the Vietnam War. Also known as Operation Irving, it took place on the low plain of Bong Son, in central Vietnam, in an area known as the Iron Triangle.
Background to the Battle of Bong Son
The South Vietnamese Army’s 22nd Division had been in pursuit of the North Vietnamese Army’s 3rd Division (2nd, 18th, and 22nd Regiments) in the Iron Triangle. As the North Vietnamese Army suddenly stopped and fought back hard, the commander of the 22nd Division, General Nguyen Thanh Sang asked for reinforcements by two South Vietnamese Army’s airborne battalions, which still were not enough. Then, the US 1st Cavalry Division, an airmobile unit of divisional strength commanded by Major General Harry Kinnard, was sent to assist.
The Battle of Bong Son began on January 28, 1966, when the 3rd Brigade of the 1st Cavalry Division, commanded by Colonel Moore, secured Bong Son airstrip, and then probed at the enemy, opening his serious operations in the area. Harry Kinnard 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 neighboring valleys, along with South Vietnamese units, to force the Communists to fall back.
The US 1st Cavalry attacked the 22nd regiment of the North Vietnamese Army’s 3rd Division from three directions. As this four-day fight wound down, Kinnard moved the US 2nd Brigade into the mountains at the An Lao valley, and the 3rd Brigade to the south end, where they were covered by artillery. United States Marines pressured the enemy force in the valley, while the South Vietnamese General Sang blocked the exists. 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 USS Uhlmann. The enemy was hit heavily by 105-millimetre (4.1 in) artillery fire from the Cavalry’s helicopter-lifted howitzers, and helicopters operated at night in fire support, supply, medical evacuation roles. AA B-52 strike also was made on the suspected 2nd Regiment command post, with limited results.
On 10 February, the 1st Cavalry’s 1st Brigade, commanded by Archie R. Hyle, flew from An Khe into the Kim Son valley. Then, the American commander 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 North Vietnamese 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 Colonel Moore’s 3rd Brigade.