Campaign 74B (2 February–30 April 1971) was a major combined arms offensive by the People's Army of Vietnam (PAVN) during the Laotian Civil War. The Communist offensive, if successful, would knock the last remaining fighting troops of the Kingdom of Laos out of the war, ensuring the Vietnamese conquest of Laos. The PAVN 316th Division—reinforced by artillery, tanks, and sappers—attacked during a period of slackened tactical air support for General Vang Pao's guerrilla army; Operation Lam Son 719 was being waged at the same time. Having captured the highly strategic Plain of Jars during Operation 74B, the Communists attackers managed to penetrate deeply enough to fire upon the main guerrilla base at Long Tieng.
Disaster was staved off by importing mercenary troops from the neighboring Kingdom of Thailand. Using aerial mobility to outmaneuver the Communists, the Royalists managed to stave off defeat until the Vietnamese had to withdraw due to lack of supplies. As the Communist offensive wilted, Vang Pao was pressured by his backers in Washington, D.C. to ramp down operations to encourage peace talks to settle the war. Vietnamization would soon cut his tactical air support still further. Yet the Communists were still poised to finish L'Armee Clandestine, and could not be ignored. The Hmong general compromised by staging an "active defense" of limited spoiling counterattacks to regain ground in the aftermath of Campaign 74B.
Overview
The French loss of the First Indochina War led to the establishment of the independent Kingdom of Laos by the 1954 Geneva Agreements. Laotian neutrality called for a ban on foreign military forces save for a French advisory mission. However, North Vietnamese troops had settled in northeastern Laos to support a Lao communist insurrection.Castle, pp. 7–12, 15–18.Dommen, pp. 30–34.
Background
A major theater of battle during the resulting Laotian Civil War was the Plain of Jars (PDJ). There Royalist Hmong guerrillas trained by the Central Intelligence Agency (CIA) and backed by air power fought it out with People's Army of Vietnam (PAVN) regulars.Ahern, p. xiv. During 1969 and 1970, a series of seesaw battles were fought on and around the PDJ. Hmong General Vang Pao directed a series of offensives dependent on air superiority blasting a way for his guerrillas. The Communists staged their own counteroffensives.Warner, pp. 44–47 Vang Pao's Operation PigfatConboy, Morrison, pp. 201–208 and Operation Raindance were countered by the PAVN's Campaign Toan Thang. Vang Pao struck back with Operation Off Balance and Kou Kiet.Conboy, Morrison, pp. 210–217. The Communists retaliated with the massive combined arms Campaign 139, running from 13 September 1969 to 25 April 1970, which nearly won them the war.Conboy, Morrison, pp. 247–260. The aptly named monarchist Operation Counterpunch, fought from 26 September 1969 through 7 January 1971, barely kept the Royal Lao Government in the war.Conboy, Morrison, pp. 265–277.
Order of battle
Campaign 139 had marked the first use of combined arms in the Laotian Civil War. Campaign 74B was the second combined arms assault, though somewhat fewer troops were allotted for 74B. The PAVN units for 74B had previously fought in Campaign 139 over the same ground. They consisted of the 316th PAVN Division, the 866th Independent Regiment, the 165th Regiment from the 312th PAVN Division, and three Dac Cong sapper battalions, backed by artillery and tanks.Conboy, Morrison, p. 295. The major difference was that all, not part, of the 312th Division had participated in Campaign 139.Conboy, Morrison, pp. 248–249. Another difference was the shortage of ammunition for the PAVN caused by air interdiction of Communist supply lines.Anthony, Sexton, p. 341.
Poised to fend off any attack was Task Force Vang Pao, a reinforced regiment of Thai mercenaries. They occupied three static positions in and around the vital guerrilla base of Long Tieng in Military Region 2; they also manned four separate artillery positions for fire support. One of these artillery units, at Ban Na, was also occupied by Bataillon Infanterie 15 (BI 15). Bataillon Infanterie 17 (BI 17) from the allied Forces Armee Neutralistes (FAN) garrisoned the forward fighter base at Muang Soui. Then there were three guerrilla regiments available for mobile operations. A Royalist guerrilla regiment, Groupement Mobile 23 (GM 23), was stationed nearby. Groupement Mobile 21 (GM 21) had been stationed at the old Project Momentum base at Ban Padong to recuperate from service in Operation Counterpunch. A third partisan regiment, GM 22, was stationed near Tha Tham Bleung.Conboy, Morrison, pp. 294–295. The Thai mercenaries were nearing the end of their year's assignment in Laos—this fact would have its effect on the unfolding tactical situation.Conboy, Morrison, p. 297.
An important constituent of the Royalist strength was tactical air power. The Royal Lao Air Force (RLAF), backed by an all out effort by their Air Commando advisers, doubled their daily sortie rate to 44. 7th Air Force (7th AF) committed 48 daily sorties, with 12 more held ready as a quick reaction force. This was a sharp contrast to the 200 sorties per day of U.S. tactical air that had been available just a few months prior during Kou Kiet. There was a concerted effort to more efficiently use such U.S. air power as was received. For air strike control, the U.S. Air Attaché promulgated a designated battle area (DBA) containing the Communist units threatening Long Tieng. The main Communist gun parks and troop staging areas could be bombed by jets using all-weather methods under Instrument Flight Rules (IFR) in certain areas. Communist bases on the Plain of Jars, down to Ban Ban, and east along Route 7 to the North Vietnamese border were free fire zones. All other air strikes would be under the existing rules of engagement, which included targets being acquired, marked and directed by Raven Forward Air Controllers operating from Long Tieng's 20 Alternate airfield.Anthony, Sexton, pp. 310, 341.
Campaign 74B
The Communist offensive
On 2 February 1971, the PAVN rained down a barrage of artillery fire on the Neutralists at the Moung Soui air base. Five of the PAVN PT-76 tanks closed for an assault. By 0600 hours 3 February, BI 17 was fleeing their stronghold, abandoning four 75mm howitzers.
The Communists next attacked a Thai artillery position at Ban Na. To discourage close air support for the Thais, the North Vietnamese moved in heavy machine guns ringing the site for antiaircraft defense. They then shelled the encircled Thais with 85 mm and 122 mm artillery rounds. They also shelled a second Thai artillery position on Zebra Ridge, as well as a Thai infantry position atop Phou Long Mat.
Foul weather, unusual for February, hindered flight operations. Taking advantage of the cloud cover, a battalion from the 866th Independent Regiment and a company of 41st Dac Cong Battalion moved down the Nam Bleung Valley. On 7 February, they struck GM 22. With the huge Operation Lam Son 719 offensive beginning against the Ho Chi Minh Trail on 8 February in southern Laos, the fighting in northern Laos suddenly rated only 24 sorties of tactical air support per day.
While the Communist battalion tied up the guerrilla regiment, 1st Company of the 27th Dac Cong Battalion infiltrated past those Royalists. Beginning at midnight 13 February, Dac Cong commandos took the major guerrilla base at Long Tieng under fire with a DK-82 recoilless rifle. This threat to the vital Royalist stronghold was diversion for another element of Dac Cong. This latter element had circled to move in from the south, headed toward the King's villa; they destroyed a 105 mm howitzer near it. The Dac Cong set up a mortar and began shelling Long Tieng. For the first time ever, the PAVN fired 122 mm and 140 mm rockets at the base. The chaotic situation was not helped by Vang Pao's overnight absence in Udorn, Thailand; the Hmong partisans of L'Armee Clandestine depended upon his orders.
If the paucity of air support were not problematic enough, on 14 February,Robbins, pp. 323–332. an F-4 Phantom II inadvertently dropped cluster munitions on civilian dependents. Thirty Hmong women and children were killed; 170 wounded. A munitions dump, a mess hall, the CIA dormitory, all were struck. Vang Pao landed back at Long Tieng in the wake of this dispiriting disaster. Also arriving were two Thai mercenary battalions, Bataillon Commando 603 (BC 603) and Bataillon Commando 604 (BC 604) which were stationed on Skyline Ridge to ward off the Dac Cong sappers.
With the PAVN onslaught moving southwestwards of the PDJ towards the Hmong heartland, Vang Pao thought of a diversionary effort east of the PDJ a la Operation Counterpunch III. Instead, his CIA backers supplied him with a guerrilla regiment imported from Military Region 3 to the south. Landed on 28 February 1971, Groupement Mobile 31 (GM 31) was tasked with sweeping north from Skyline Ridge overlooking Long Tieng. They swept north toward the refugee center at Sam Thong. However, the operation's start was delayed by insubordination among the troops. Desertions began from Bataillon Guerrier 318 (BG 318) and Bataillon Guerrier 308 (BG 308) on 6 March. BG 318 refused its duties for two days until they were paid their overdue salaries. BG 308 retreated to Long Tieng with a bill of complaints. They were appeased by relief of their commanding officer and the elevation of his deputy. Only after those matters were settled did the guerrillas resume operations.Conboy, Morrison, pp. 295–296.
On 3 March, two more offensive Thai mercenary battalions, Bataillon Commando 605 (BC 605) and Bataillon Commando 606 (BC 606), landed at Long Tieng. Fending off Vang Pao's notion that the Thai units should be reduced to platoon-size reinforcements for Hmong guerrillas units, the CIA advisers lumped the newly arrived battalions together with the two battalions on Skyline Ridge as Task Force Singha. BCs 605 and 606 swept north to Sam Thong with little opposition.Conboy, Morrison, p. 296
On 9 and 10 March, BG 308 was helicoptered back to its line of departure at Sam Thong to resume moving towards its objective, the Nam Ngum (Ngum River). On 15 March, Task Force Singha gained two more Thai units, Bataillon Commando 601 (BC 601) and Bataillon Commando 602 (BC 602). The newly arrived battalions were directed against Phou Tham Seh, a high point three kilometers north of Skyline Ridge. Despite being overburdened with weighty weaponry, drenched by rain, and chilled by freezing nights, they took the ridge.
On 19 March, BC 605 and BC 606 were helilifted into the Tha Tham Bleung Valley; their objective was nearby Ban Hintang. The next day, GM 31 reached the bank of the Nam Ngum. BC 605 and BC 606 would have no such luck in achieving their objective. They clashed twice with the PAVN before withdrawing southward on 27 March to friendly positions on Zebra Ridge.
Meanwhile, during the furor of battle, Bataillon Artillerie 635 (BA 635) arrived to relieve the artillery positions on Zebra Ridge and the western end of Skyline Ridge. Brown smog from swidden farming clogged the atmosphere, inhibiting the use of such little air support that was available.