Siam Renamed Thailand

On June 23, 1939, Prime Minister Field Marshal Plaek Phibunsongkhram (Phibun) officially changed the country's name from Siam to Prathet Thai — Thailand, meaning "Land of the Free." The renaming was part of Phibun's sweeping Cultural Mandates (Ratthaniyom), a nationalist modernization program modeled partly on the authoritarian regimes of Europe and Japan. Phibun promoted the idea of a unified "Thai race," mandated Western-style dress, discouraged Chinese language use, and encouraged citizens to adopt Thai surnames. When World War II reached Southeast Asia, Phibun allied Thailand with Japan in January 1942, making it the only Southeast Asian nation to formally join the Axis powers. In exchange, Japan allowed Thailand to annex territories in Laos, Cambodia, and Malaya. A clandestine anti-Japanese resistance movement, the Free Thai Movement (Seri Thai), operated simultaneously. After Japan's defeat, the Free Thai Movement's existence helped Thailand avoid being treated as a defeated enemy. The country briefly reverted to "Siam" from 1945 to 1948, before Phibun — back in power through yet another coup — restored the name Thailand permanently.