Souphanouvong, Prince (sōfäˈnōvŏngˌ) [key], 1909–95, Laotian government official; half-brother of Prince Souvanna Phouma. Although a member of Laos's royal family, he was an active nationalist and fought the French as a member of the pro-Communist Pathet Lao. After Laos gained independence, he joined (1958) a coalition cabinet. Arrested after rightists took power in 1959, he escaped in 1960 to lead the Pathet Lao forces in opposition. He was a Pathet Lao delegate to the Geneva Conference on Laos (1961–62), and in the resulting coalition government he was vice premier and minister of economic planning. When the coalition fell to renewed fighting (1963), Souphanouvong rejoined the Pathet Lao. In 1973, an agreement was reached with Souvanna Phouma ending the fighting, and a new coalition government was formed (1974) with Souphanouvong heading an advisory body. When the Pathet Lao came to power as a result of the North Vietnamese victory in Vietnam in 1975, Souphanouvong became president of Laos. He resigned in 1986.