Troops from the People's Army of Vietnam (PAVN) and the Pathet Lao attacked Hmong recruits being trained as Auto Defense Choc guerrillas via Operation Momentum.

Although the Hmong made the tactical error of defending a fixed position, their eventual escape from the communist invaders left their fledgling L'Armee Clandestine intact and able to wage war for the Royal Lao Government.

As the First Indochina War ended, and the Kingdom of Laos moved towards independence, the departing French bureaucrats and soldiers were gradually replaced by Americans.

[1] Captain Kong Le, who was opposed to foreign involvement in his nation's affairs, staged a coup d'etat on 9 August 1960.

In the wake of Phoumi's ascension, James William Lair of the Central Intelligence Agency secretly entered Laos.

On 9 January 1961, Lair helicoptered out to Ta Vieng on the Plain of Jars to meet a young Hmong lieutenant colonel of the Royal Lao Army named Vang Pao.

[5] With this in mind, Lair took the offer back to his superior, Desmond Fitzgerald, with the observation that Vang Pao already had gathered 4,300 potential Hmong recruits.

[4] The village of Ban Pa Dong was selected as the base for covert training of Hmong guerrillas for several reasons.

Flying in to begin the first Operation Momentum instruction cycle, the Air America H-34 carrying Lair ran out of lift to clear a ridge-line.

Vang Pao's call for recruits rallied entire Hmong villages to Padong so the eligible males could undergo guerrilla training.

"[9] The original basis of Momentum was the use of a three-day threshold of opportunity to train Hmong guerrillas before the PAVN could attack from the Plain of Jars.

By 31 January, early graduates of the ADC program had patrolled 30 kilometres (19 mi) into enemy territory, killing a dozen Pathet Lao and bringing back eight captured weapons.

[14] The head of the Programs Evaluation Office, General Andrew Boyle, also believed Ban Pa Dong should not be held.

Ten days later, in a demonstration of their relentless tactics versus fixed positions, the PAVN overran and wiped out the Royalists at Muong Ngat some 125 kilometres (78 mi) east of the Momentum site.

[17] As local tribes burned off undergrowth to clear fields for their slash-and-burn agriculture, visibility worsened, hampering aerial support for the Hmong.

[19][20] According to one version, the forwarded radio intercept came in at 15:00 hours, warning of an imminent assault on a company posted about 2 kilometres (1.2 mi) south of the Lima 5 airstrip.

Shirley, Chance and his U.S. Special Forces Team, and the PARU cadre hurriedly destroyed any military gear too heavy to carry, and herded the Hmong away from the flaming village.

[20] Carrying their wounded, with the Americans and the PARUs as a rear guard and heavy small arms fire popping overhead, 400 to 500 Hmong of all ages and both genders began a dispersal into the gloom.

[23] The results of this first defense of a fixed position did not deter Vang Pao from repeating this error in future years, as at the battle of Na Khang.

[24] Nevertheless, Ban Pa Dong had served an important purpose; the first 5,000 ADC troopers trained there were the basis of Vang Pao's L'Armee Clandestine.