led to the signing of the Bowring Treaty, the first of many unequal treaties with Western countries. This, however, brought trade and economic development to Siam. The unexpected death of Mongkut from malaria led to the reign of underage Prince Chulalongkorn, with Somdet Chaophraya Sri Suriwongse (Chuang Bunnag) acting as regent. Chulalongkorn (r. 1868–1910) initiated centralisation, set up a privy council, and abolished slavery and the corvée system. The Front Palace crisis of 1874 stalled attempts at further reforms. In the 1870s and 1880s, he incorporated the protectorates up north into the kingdom proper, which later expanded to the protectorates in the northeast and the south. He established twelve krom in 1888, which were equivalent to present-day ministries. The crisis of 1893 erupted, caused by French demands for Laotian territory east of Mekong. Thailand is the only Southeast Asian nation never to have been colonised by a Western power, in part because Britain and France agreed in 1896 to make the Chao Phraya valley a buffer state. Not until the 20th century could Siam renegotiate every unequal treaty dating from the Bowring Treaty, including extraterritoriality. The advent of the monthon system marked the creation of the modern Thai nation-state. In 1905, there were unsuccessful rebellions in the ancient Patani area, Ubon Ratchathani, and Phrae in opposition to an attempt to blunt the power of local lords. The Palace Revolt of 1912 was a failed attempt by Western-educated military officers to overthrow the Siamese monarchy. Vajiravudh (r. 1910–1925) responded by propaganda for the entirety of his reign, which promoted the idea of the Thai nation. In 1917, Siam joined the First World War on the side of the Allies. In the aftermath Siam had a seat at the Paris Peace Conference, and gained freedom of taxation and the revocation of extraterritoriality. Constitutional monarchy, World War II and Cold War A bloodless revolution took place in 1932, in which Prajadhipok was forced to grant the country's first constitution, thereby ending centuries of feudal and absolute monarchy. The combined results of economic hardships brought on by the Great Depression, sharply falling rice prices, and a significant reduction in public spending caused discontent among aristocrats. In 1933, a counter-revolutionary rebellion occurred which aimed to reinstate absolute monarchy, but failed. Prajadhipok's conflict with the government eventually led to abdication. The government selected Ananda Mahidol, who was studying in Switzerland, to be the new king. Later