Launched from a rendezvous point near Vang Tai, Laos, on 2 July 1970 as a three-battalion assault on the major People's Army of Vietnam (PAVN) transshipment center at Tchepone, Laos, it ran into stiff resistance from the PAVN 9th Regiment from 11–15 July.

Although ancillary follow-up operations occurred in the vicinity throughout September, the Maeng Da offensive would not resume.

However, the Central Intelligence Agency, which had trained and supported the Royalist guerrilla battalions, prepared the Tchepone Operation to follow it.

When France withdrew most of its military in conformity with the treaty, the United States filled the vacuum with purportedly civilian paramilitary instructors.

Invading during the opium harvest season of 1953, a North Vietnamese communist force settled in northeastern Laos adjacent to the border of the Democratic Republic of Vietnam.

Meanwhile, the Annamese Cordillera in southern Laos became the haven for a logistics network, the Ho Chi Minh trail.

It also served as a test of the Central Intelligence Agency-sponsored Mobile 1 battalion that had been raised for service beyond its parent Military Region 3 (MR 3).

The CIA trainers were contemptuous of their urban recruits; their disdain was reflected by the fact that a Lao slang meaning of the term "maeng da" is "pimp".

Instead, they spent 11–15 July heavily engaged with People's Army of Vietnam 9th Regiment regulars, with Black Battalion taking severe casualties.

The hurly-burly of tactical aircraft supporting the landed troops made the air space surrounding the HLZ exceedingly hazardous.

When the air attache briefed the meeting on the progress of Maeng Da, the CIA Station chief was humiliated to discover he had not been previously informed of the attack.

[10] The assault on the Ho Chi Minh Trail choked up supply traffic while it lasted; to the Americans, that was a success.