October 23 or Wan Piyamaharat ( Chulalongkorn day) commemorates King Chulalongkorn (Rama V), the anniversary of his death. King Chulalongkorn the Great or Rama V, was the fifth king of the Chakri dynasty of Thailand. He is regarded as one of the greatest kings of Siam.
King Chulalongkorn modernized the government by introducing a cabinet system, and the semi-feudal provincial administration was changed into a modern administration with provinces (changwat) and districts (amphoe) as it still is today. He declared amnesty for all political prisoners, and also gradually abolished slavery. He also introduced banknotes.