However, seniors posts were gradually filled with one 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 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.
In 1917 Siam declared war on Germany, mainly to gain favour with the British and the French. Siam's token participation in World War I gained it a seat at the Versailles Peace Conference, and Foreign Minister Devrawongse used this opportunity to argue for the repeal of the 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 the fact that the king had no son; he obviously preferred the company of men to women (a matter which of itself did not much concern Siamese opinion, but which did undermine the stability of the monarchy).
Thus when Rama VI died suddenly in 1925, aged only 44, the monarchy was already in a weakened state. He was succeeded by his younger brother Prajadhipok.