In 1941 the French fought a war with the Thais for Laotian territory. The Japanese forced an armistice and parts of Laos were given to Thailand. Then in April 1945 the Japanese forced the pro-French king Sisavang Vong to declare independence from France. Following the Japanese surrender in September 1945 prince Phesarath was prime minister of Laos. He headed a government called Lao Issara (free Lao).
However Laotian independence did not last long. In March 1946 the French invaded Laos and by May 1946 they were in control of the country again.
Then in 1950 the Pro-Communist Prince Souphanouvong formed an organisation that became known as Paphet Lao (Land of the Lao). At first it was a relatively small organisation backed by the Viet Minh.