梭发那·富马亲王
On 18 April 1964, Prime Minister Souvanna Phouma met with his brother Souphanouvong, leader of the Lao communists, on the Plain of Jars. The Pathet Lao demanded demilitarization of both Luang Prabang and Vientiane as the price of their participation in a national government. This discouraged Souvanna Phouma, who returned to Vientiane, having decided to resign as Prime Minister. However, King Sisavang Vatthana would not approve the resignation until the next day.