King of the waters describes how a brilliant Dutch engineer ultimately failed to implement his plans for modern irrigation in Siam. Homan van der Heide’s identification with the interests of the rice farmers caused ambivalent reactions from his Siamese environment. Interwoven with the detailed description of the actions of the Dutch engineer, King Chulalongkorn and some of his ministers is the ambiguous performance of the Siamese state towards agriculture in the first decade of the twentieth century. The book shows the weight of many contingencies in state affairs, especially through the problematical interactions between the engineer Homan van der Heide and the minister of Agriculture, chao phraya Thewet — they seemed to form a kind of jolie à deux. King of the waters sketches a dramatic picture of clashing cultures, comparable to many encounters in contemporary development cooperation. The study is based on archival material in the National Archives in Bangkok and documents available in the Netherlands.