Operation Phou Phiang II (6 August – 25 October 1972) was one of the final battles of the Laotian Civil War. It was an attempt to relieve the siege on the guerrilla headquarters at Long Tieng on the Plain of Jars. It was designed as a two phase attack consisting of five task forces of Thai mercenaries and Royalist guerrillas upon the People's Army of Vietnam invading Laos. Air superiority was used to direct over 100 air strike sorties daily to support the offense, and air mobility to shuffle attacking troops. A new radar bombing program by F-111 Aardvarks and B-52 Stratofortresses failed to cripple the Communist forces. Designed to overwhelm Communist defenses with its multiplicity, the five Lao task forces were defeated in detail by the Communists despite two new columns being improvised and introduced into the fray.
Key to the Lao defeat was the lack of competent staff work to coordinate the operation, the immaturity and carelessness of their troops, as well as a widespread outbreak of trench foot.
Overview
The Kingdom of Laos contained a Communist insurrection from its moment of independence. U.S. financial and military support of Laos began in 1953, and intensified through the succeeding years as the Laotian Civil War heated up.Castle, pp. 7–19. In 1961, the Central Intelligence Agency began arming and training hill tribes guerrillas on and around the strategic Plain of Jars.Warner, pp. 53–52. The Hmong soldiers of L'Armée Clandestine would fight the invading People's Army of Vietnam until the ceasefire of February 1973.Ahern, pp. xiv–xv.
Background
In the aftermath of the January 1972 Campaign Z, and its two counters, Operation Strength I and Operation Strength II, the strategic Lao guerrilla base at Long Tieng was at serious risk of capture by the People's Army of Vietnam (PAVN) until the rainy season gummed up military operations. Royalist radio intercepts began reporting the withdrawal of the PAVN 312th Division as early as 26 April 1972. On 17 May 1972, the rains came. The 312th Division had been withdrawn from the Plain of Jars (PDJ) to fight in the Easter Offensive striking South Vietnam; this considerably weakened the Communist forces in northern Laos. The Vietnamese Communist supply lines began to literally bog down and wash out in the monsoon downpour.Conboy, Morrison, p. 343.
Order of battle
PAVN strength was reduced to four regiments; however, they had supporting arms. The 174th Regiment garrisoned Phou Phasai, Zebra Ridge, and a regimental headquarters. The 866th Independent Regiment occupied the Plain; it was supported by pairs of T-34 and PT-76 tanks, and of 85 mm and 122 mm field guns. The 148th and 335th Independent Regiments were reserve units. The 42nd Artillery Battalion had its ten artillery pieces manning three fire bases. Also available were two sapper units, the 27th and 421st Dac Cong Battalions; three anti-aircraft battalions; an armored unit equipped with six T-59 and two T-34 tanks, as well as four K-63 armored personnel carriers.Conboy, Morrison, p. 344.
Opposed to them were a bewildering hodgepodge of Royalist Hmong guerrillas and Thai mercenaries in shifting assignments and alignments. During April and May 1972, three regimental-size guerrilla Groupements Mobile (GMs) were circulated south into Thailand for refurbishing—GMs 24, 23, and 22. Task Force Vang Pao, a formation of Thai mercenaries, contained at least six battalions. Five guerrilla battalions were stationed at Ban Pa Dong—Bataillons Guerrier (BGs) 105, 110, 209, 228, and 233. Another guerrilla battalion, BG 224, was stationed on Skyline Ridge, overlooking Long Tieng. Two reinforcement regiments would arrive from neighboring Military Region 3—GM 30 would be flown in on 18 May; GM 31 arrived on 2 July.Conboy, Morrison, pp. 343–344.
Air superiority for the guerrillas would be guaranteed. They were allotted up to 80 Royal Lao Air Force (RLAF) T-28 Trojan sorties daily for close air support. The U.S. Air Force pledged 20 daily close air support sorties by F-4 Phantom IIs and six by A-1 Skyraiders. Ten more Phantom sorties were promised for interdiction missions. The operation's daily air support also included a B-52 Arc Light strike (with two more on call), as well as one AC-130 and four AC-119 gunship sorties.Conboy, Morrison, p. 347.
Preliminary activities
With PAVN strength reduced to four regiments, the Royalist forces felt free to both refit their worn units and push the Vietnamese for territory. On 8 May, two Royalist columns moved out; one was aimed at Sam Thong, the other at Phou Phasai. On 11 May 1972, six Bataillons Commando (BCs) of Thai mercenaries recaptured the refugee relief center at Sam Thong; they established two artillery fire bases in the vicinity.
The Phou Phasai probe was a different matter. On 22 May, two Thai BCs that had been withdrawn in the midst of Operation Sinsay joined the fresh reinforcements of GM 30 to attack the mountaintop position the PAVN valued as a base for assaults on the Royalists. On the 25th, they were halted by the fresh PAVN troops that had manned the hilltop, and stalemated.
In late May, Laotian General Vang Pao flew to Washington, DC to lobby for support for an offensive. He updated William H. Sullivan, with whom he had worked for four years. Sullivan was noncommittal. Melvin Laird had some issues with the use of B-52 Stratofortresses as tactical air power. On the other hand, in a White House meeting with Henry Kissinger, he found an enthusiastic proponent for an offensive. Stuart Symington led the general to believe financial backing for the Laotian War would not be curtailed. With this backing, Vang Pao returned to Laos and to his war in Military Region 2.Ahern, pp. 461–462.
GM 31 arrived on 2 July, and captured two hills overlooking a new PAVN supply road, Route 54. On 16 July, as GM 30 rotated out of action, GM 31 launched an assault on Phou Phasai from a differing direction. A variety of battalion-size assaults met with no more success.
Operational planning
Operation Phou Phiang II (Operation Plateau II) was planned at Udorn Royal Thai Air Force Base on 26 July 1972. Hmong General Vang Pao met with his two senior CIA advisers and the Thai general in charge of supplying mercenary troops to the "Secret War" in Laos. The tribal leader was worried about the Communist troops' continuing proximity to the guerrilla main base at Long Tieng.Conboy, Morrison, p. 345.
For once, Vang Pao's American backers did not try to discourage a wet season offensive. Planning was based on the assumption that Vang Pao would have at least 11, and possibly 13, regiments available to him by mid-September 1972. By launching five small attacks, it was hoped that the Communist would be too overwhelmed to concentrate on one of them. A two phase plan of attack was formed. Phase one, planned to start on 15 August, would draw PAVN reinforcements southwestward of the Plain of Jars while capturing the mountaintop position at Phou Seu. Then, two regiments of guerrillas would be landed in the vacuum behind the front lines thus caused by the PAVN's forward movement. Phase two would follow on with two road interdictions planned to starve out the PAVN, followed by establishment of an interlocking network of artillery fire bases after the Communists withdrew. Not figured in the Royalist calculations was the determination of PAVN General Vũ Lập to alter Communist policy and maintain PAVN's positions on the Plain through the rainy season monsoon.Conboy, Morrison, pp. 344–345.
August–September 1972 operations
Vang Pao jumped the gun to begin his operation in early August. He organized his attacking troops into five separate task forces. He struggled to coordinate the start of the task force assaults over the first three weeks in August. By the time Phou Phiang II was a week old, PAVN reactions were not following the Royalist planners' expectations. The offensive was in trouble.
With his assault schedule thrown out of whack by the PAVN, and his troops consequently in trouble, Vang Pao went looking for help. On 1 September, he made an emergency flight to Vientiane for a tense meeting with Ambassador G. McMurtrie Godley at the airfield. Hoping to cadge more air support, the general blamed a shortage of tactical air for the offensive's lack of success. From Godley's standpoint, the Hmong unit commanders left much to be desired for combat leadership of a force crippled by trench foot. The ambassador made it clear that U.S. tactical air support was limited to 18 daily sorties. He then asked if Vang Pao would continue the offensive on those terms. At this, Vang Pao returned to battle, knowing that saving Long Tieng was essential for the Royalists.Ahern, p. 463.
On 19 September, the CIA station in Vientiane reported to Headquarters in the U.S. that the PAVN were successfully adapting the Hmong guerrilla small unit tactics of harassing opposing troop concentrations. They were trying "not only to blunt Vang Pao's offensive, but to wipe him out...."Ahern, p. 466.
Task Force Alpha
Task Force Alpha was formed from Groupement Mobile 31 (GM 31) and two available Thai mercenary battalions, Bataillon Commando 607A (BC 607A) and Bataillon Commando 609A (BC 609A). It consisted of 3,700 troops. They were launched at Communist strongholds at Ban Hintang and Phou Phasai. By 6 August 1972, the Royalist attacks had been repulsed, and the attack turned into a defense of the positions already held by Alpha.Conboy, Morrison, p. 346.Ahern, p. 464.
On 18 August, Task Force Alpha renewed its offensive moves. Other than securing some high ground near Hill 1800, it had no success during its week's operations.
On 5 September, Task Force Alpha was weakened to impotence when GM 31 was withdrawn to Savannakhet for refurbishing.
Task Force Bravo
Task Force Bravo consisted of Groupement Mobile 22 (GM 22), numbering 1,200 men. Its CIA adviser was James Parker, call sign Mule. On 11 August, they were helilifted to Than Heup. They moved east to their objective, occupying it on 15 August. That same day, the 7th and 8th Battalions of the PAVN 866th Regiment moved in to block further Royalist advance, sparking a fortnight of fighting.Conboy, Morrison, pp. 346, 348.
When the PAVN battalions shifted to strike Task Force Delta, GM 22 occupied more of the Plain of Jars. On 1 September, the Thai Battalion Commando 619A (BC 619A) was helicoptered in to occupy the mountaintop of Phou Then within the new GM 22 area of operations. When the 335th Regiment turned from its victory over Task Force Delta to attack Task Force Bravo, clearing weather allowed tactical air strikes to help defeat the assault. On 11 September, the task force was reinforced by a pair of 105 mm howitzers and GM 30—imported from Military Region 3 (MR 3).
At 0720 hours on 26 September, PAVN artillery and infantry struck, destroying one of the howitzers. By noon, the guerrilla regiments were withdrawing westward with the Thais in trail. A hastily regrouped GM 21 was helilifted in three kilometers south of GMs 22 and 30 on the 27th to back up Bravo.Conboy, Morrison, p. 349.
Task Force Charlie
On 13 August, Task Force Charlie was helilifted to a soggy landing zone in a tight little valley southeast of the Plain. Consisting of GM 23's 1,200 soldiers, the task force objective was 11 kilometers west of them, at the Jungle's Mouth. In late August, the 4th Battalion, PAVN 148th Regiment attacked the Royalist regiment. The Royalists withdrew to nearby Khang Kho as September began.