Prince Vajiravudh was born on 1 January 1880 to Chulalongkorn and one of his four queens, Saovabha. In 1888, upon coming of age, Vajiravudh received the title Krom Khun Thep Dvaravati. He was firstly educated in the Royal Palace in Siamese and English language. In 1894, his half-brother Crown Prince Vajirunhis died, and Vajiravudh was appointed the new Crown Prince of Siam. He continued his education in Britain, at the Royal Military College, Sandhurst, in 1898, and was commissioned briefly into the Durham Light Infantry upon graduation. He studied law and history at Christ Church, Oxford, in 1899, where he was a member of the exclusive Bullingdon Club. However, he suffered from appendicitis that barred him from personally graduating in 1901. On behalf of his father, King Chulalongkorn, he attended the coronation of King Edward VII on 9 August 1902.[1]
Crown Prince Vajiravudh returned to Siam in 1902 and in 1904 became a temporary monk, according to Siamese traditions. In 1906, his father Chulalongkorn travelled to Europe to seek treatment for his lung disease, and Chulalongkorn made Vajiravudh Regent of Siam. One of Crown Prince Vajiravudh's accomplishments during this regency was his supervision of the construction of the Chulalongkorn Equestrian Statue.
Chulalongkorn died on 23 October 1910, and Vajiravudh succeeded his father as king of Siam.