On March 27, 1975, North Vietnamese-Pathet Lao forces launched a strong attack against Vang Pao's Hmong defenders. The attackers rapidly captured the Sala Phou Khoun road junction and then drove south along Route 13 as far as Muang Kasi. Souvanna Phouma, wishing to avoid bloodshed, ordered Vang Pao only to defend himself and refused to allow air strikes in his support. The Pathet Lao singled out the Hmong as enemies to be shown no quarter. Pathet Lao radiobroadcasts spoke of "wiping out" these special forces who had stood in their way for fifteen years.

Realizing that the Hmong were being abandoned and the penalty they faced if left to the mercy of the Pathet Lao, Vang Pao requested evacuation for his soldiers and their families to safe haven in Thailand. The CIA station at Udon Thani offered to evacuate families of key officers. Vang Pao requested an airlift for 5,000. Facing an ultimatum, Vang Pao and twelve Hmong leaders signed a treaty on May 10 reminding the United States of the pledges made to them and agreeing to leave Laos and never return. In the next days a motley collection of planes piloted by United States volunteers, Hmong, and Lao flew out a few hundred Hmong. Vang Pao himself left on May 14, eluding the T-28s at Vientiane.

Meanwhile, a campaign of intimidation against rightist members of the PGNU and military officers gathered momentum in Vientiane. Operating under the umbrella of a coalition of twenty-one "organizations standing for peace and national concord," a standard communist tactic, the demonstrators used inflation and other popular grievances to mobilize support for the eighteen-point program of the National Political Consultative Council. Souvanna Phouma tried at first to ban the demonstrations but later gave in and sided with their aims. The May Day holiday provided the pretext for the largest demonstration to date, followed a week later by a demonstration against the rightist army and police. Demonstrators occupied the compound of the United States aid mission, forcing termination of the aid program. Four rightist ministers, including the defense minister, Sisouk na Champasak, fled. Another minister, Boun Om, was assassinated in the capital.

Elsewhere, takeovers of government offices and orchestrated demonstrations led to the entry of Pathet Lao troops into Pakxé, Savannakhét, Thakhek, and other towns during May "to secure their defense." People's revolutionary committees surfaced to seize administrative power from the remnants of the RLG. Officials and military officers who chose not to flee were summoned to "seminars." On August 23, the Pathet Lao completed its seizure of local power with the takeover of the Vientiane city administration by a revolutionary committee. The Pathet Lao announced that military units had requested Pathet Lao "advisers," thereby facilitating the integration of the army.

Throughout this time, the elite communist leaders who were making the decisions remained out of sight. Kaysone Phomvihan, in a speech in Vieng Xay on October 12, declared that "the revolution will speed up." Simultaneously, the National Political Consultative Council established new screening procedures for candidates for election that effectively eliminated all those who had not supported the LPF. Suddenly, in the last week of November, the NPCC convened in Xam Nua. Also in November, elections were held in the "new zone," the former RLG zone. Eligible voters were required to vote for a list of candidates whose names were distributed the evening before. Candidates were local party administrators, whose identities had been kept secret up to then. On November 28, demonstrators demanded the dissolution of the PGNU and the National Political Consultative Council as inappropriate to the situation. The next day, Souvanna Phouma and Souphanouvong flew to Louangphrabang and persuaded the king to abdicate.

Data as of July 1994