| Conflict: | Operation Austin IV |
| Partof: | Vietnam War |
| Date: | 1–18 May 1966 |
| Place: | Phước Long Province, South Vietnam |
| Result: | U.S. claims operational success |
| Combatant1: |  United States |
| Combatant2: | North Vietnam |
| Commander1: | BG Willard Pearson Lt.Col. Henry E. Emerson |
| Commander2: | |
| Units1: | 1st Brigade, 101st Airborne Division 173rd Airborne Brigade |
| Units2: | 141st Regiment |
| Casualties1: | 9 killed |
| Casualties2: | US body count: 101 killed 148 estimated killed 6 captured |
Operation Austin IV was a search and destroy operation conducted by the 1st Brigade, 101st Airborne Division and the 173rd Airborne Brigade in western Quang Duc and Phước Long Provinces, from 1 to 18 May 1966.[1]
Operation Austin IV was a search and destroy operation near the Cambodian border in II Corps.[1]
On 1 May the 2nd Battalion, 502nd Infantry Regiment conducted a helicopter assault near Bu Prang Camp and patrolled the area until 6 May without making any contact with the PAVN. Also on 1 May the 1st Battalion, 327th Infantry Regiment was deployed by helicopter onto 2 infiltration routes from Cambodia and patrolled the area until 8 May without making any contact.[2]
On 6 May following intelligence indicating the presence of enemy forces near the abandoned Special Forces base at Bù Gia Mập, the 2/502nd was moved from Bu Prang to Bù Gia Mập and were joined by A Troop 17th Cavalry Regiment on 8 May and the 1/327th on 10 May. On 10 May Company A, 2/502nd captured a soldier from the PAVN 141st Regiment who revealed that 4 companies of his unit were waiting in an ambush nearby. On 11 May Company A, 2/502nd and A/17th Cavalry encircled the PAVN ambush position and then called in air and artillery strikes, which resulted in claims of the destruction of most of a PAVN battalion.[3] [2]
On 14 May a B-52 strike took place northwest of Bù Gia Mập and 2/502nd and 2nd Battalion, 503rd Infantry Regiment were sent into the area to exploit the strike but met only scattered resistance. On 17 May 2/502nd was flown out of Bù Gia Mập to Nhon Co, while 2/503rd was flown by helicopter to Sông Bé Base Camp. On 18 May 1/327th was flown out to Nhon Co.[2]
Operation Austin IV officially concluded on 18 May, with the US claiming PAVN losses were at 101 killed, 148 estimated killed and 6 captured, U.S. losses were 9 killed.[2]