for the education of the whole populace, the setting up of clinics where free vaccination was given against smallpox, and the continuing expansion of railways. However, senior posts were gradually filled with members of the king's coterie when a vacancy occurred through death, retirement, or resignation. By 1915, half the cabinet consisted of new faces. Most notable was Chao Phraya Yomarat's presence and Prince Damrong's absence. He resigned from his post as Minister of the Interior officially because of ill health, but in actuality because of friction between himself and the king. World War I In 1917 Siam declared war on Germany and Austria-Hungary, mainly to be favor with the British and the French. Siam's taken participation in World War I secured it a seat at the Versailles Peace Conference, and Foreign Minister Devawongse used this opportunity to argue for the repeal of 19th century treaties and the restoration of full Siamese sovereignty. The United States obliged in 1920, while France and Britain delayed until 1925. This victory gained the king some popularity, but it was soon undercut by discontent over other issues, such as his extravagance, which became more noticeable when a sharp postwar recession hit Siam in 1919. There was also concern that the king had no son, which undermined the stability of the monarchy due to the absence of heirs. Thus when Rama VI died suddenly in 1925, aged only 44, the monarchy was in a weakened state. He was succeeded by his younger brother Prajadhipok. Transition to 1932 revolution Unlike other states of Southeast Asia, Thailand was never formally colonised by colonial powers, although significant territory had been ceded under duress to Britain and France. Conventional perspectives attribute this to the efforts made by the monarchs of the Chakri Dynasty, particularly Rama IV and Rama V, to "modernise" the Siamese polity, and also to the relative cultural and ethnic homogeneity of the Thai nation. Rama IV (King Mongkut) opened Siam to European trade and began the process of modernisation. His son, Rama V (King Chulalongkorn), consolidated control over Thai vassal states, creating an absolute monarchy and a centralised state. The success of the Chakri monarchs would sow the seeds of the 1932 revolution and the end of the absolute monarchy. "Modernisation" mandated from above had, by the early 20th century, created a class of Western-educated Thais in the commoner and lower nobility classes, who staffed the