Field Marshal Plaek Phibunsongkhram

Field Marshal Plaek Phibunsongkhram was one of the leaders of the 1932 revolution that ended absolute monarchy in Siam. He later went on to rule the country as prime minister and then dictator from 1938–1944, and 1948–1957. During this time, there were many initiatives to increase Thai nationalism and improve (in his opinion) the culture of the country. The Wikipedia article about Plaek Phibunsongkhram states that during his rule
“a series of Cultural Mandates were issued by the government. These mandates encouraged that all Thais were to salute the flag in public places, know the new national anthem, and use the Thai language, not regional dialects. People were encouraged to adopt western attire, as opposed to the traditional dress of Thai men and women. Similarly, people were encouraged to eat with a fork and spoon, rather than their traditional hands. In Phibunsongkhram’s perspective, these policies were necessary for Thailand to change the minds of foreigners that Thailand was an undeveloped and barbaric country. In the interest in progressivism, Thailand needed to be recognized by foreigners as a civilized and modernized country.
In 1939, Phibunsongkhram changed the country's name from Siam to Thailand. In 1941, in the midst of World War II, he decreed January 1 the official start of the new year instead of the traditional April 13.”