Con Thien (Tiếng Việt: Cồn Tiên, meaning the “Hill of Angels”), was a United States Marine Corps combat base located near the Vietnamese Demilitarized Zone about 3 km from North Vietnam. It was the site of fierce fighting from February 1967 through February 1968.
On 27 February 1967, in response to Marine artillery fire into and the area north of the DMZ (Operation Highrise) NVA mortar, rocket and artillery fire hit Con Thien and Gio Linh. On 20 March, NVA began shelling Con Thien and Gio Linh which continued sporadically for the next two weeks. On 24 March 1st Battalion, 9th Marines began Operation Prairie III where they encounted an NVA battalion in a bunker complex southeast of Con Thien. After a two hour fight the NVA withdrew leaving 33 killed in action. Sergeant Walter K. Singleton was posthumously awarded the Medal of Honor for his actions in the attack. 3rd Battalion, 3rd Marines (3/3) operating beside 1/9 encountered an entrenched NVA Company, killing 28 NVA including two women.
In mid-April Charlie Company, 11th Engineer Battalion was tasked with clearing a 200m wide strip from Con Thien to Gio Linh, a distance of 10.6 km. The engineers were protected by a task force consisting of the 1st Battalion, 4th Marines, an AMTRAC (LVT-5) platoon, a platoon of M42 Dusters from the 1st Battalion, 44th Artillery and some ARVN units. By 19 April, despite harassment from NVA mines, small arms, recoilless rifle, mortar and artillery fire the strip was half-completed.
In order to protect Route 561, the supply line to Con Thien from Route 9, the Marines had established two outposts, C-2 Base was located 3 km southeast of Con Thien and contained artillery and infantry positions, while C-2A nicknamed the Washout was on low-lying ground overlooking a bridge.
8 May, at 03:00 some 300 rounds of mortar and artillery fire hit the base, while NVA sappers with Bangalore torpedoes breached the perimeter wire. At 04:00 two battalions of the 812th NVA Regiment armed with flamethrowers attempted to overrun the base. At the time of the attack the base was defended by the command element and Companies A and D of 1/4 Marines and a CIDG unit. The attack fell primarily on Company D. A relief column from Company A was sent with an M42 Duster, 2 LVT-5s and 2 1/4 ton trucks. The M42 was hit by an RPG-7 and an LVT-5 and one truck were destroyed by satchel charges. By 09:00 the NVA had withdrawn leaving 197 KIA and 8 prisoners. The Marines had suffered 44 KIA and 110 wounded.
After the 8 May attack, recognizing that the NVA were using the DMZ as a sanctuary for attacks into I Corps, Washington lifted the prohibition on US forces entering the DMZ and MACV authorized the III Marine Amphibious Force (III MAF) to conduct combat operations into the southern half of the DMZ.
From 13–16 May, 1/9 Marines cleared Route 561 from Cam Lo to Con Thien fought a well-entrenched NVA force south of the base. The NVA subsequently withdrew into the DMZ.
III MAF proceeded to plan a series of combined operations with ARVN forces that occurred from 18 to 26 May. Under Operation Hickory 3rd Marines’ advanced to the Ben Hai River. Under Operation Lam Son 54 the 1st ARVN Division advanced parallel to 3rd Marines while the amphibious Special Landing Force Alpha secured the coastline south of the Ben Hai River under Operation Beau Charger and Special Landing Force Bravo linked up with 3rd Marines under Operation Belt Tight. Once at the Ben Hai River, the forces swept south on a broad front to Route 9.
From 19 to 27 May when Lam Son 54 ended the ARVN were in constant contact with the NVA. The ARVN suffered 22 KIA and 122 wounded, while the NVA suffered 342 KIA and 30 captured.
The amphibious element of Operation Beau Charger met no opposition while the heliborne assault dropped into a hot LZ. Only one platoon was landed and it remained isolated until rescued several hours later. Beau Charger continued until 26 May with minimal contact. 85 NVA were killed.