Chulalongkorn and the foundations of modern ThailandMongkut was succeeded by his 15-year-old son Chulalongkorn (Rama V; ruled 1868–1910). Because of Chulalongkorn's youth, the country was ruled by a regent until the prince came of age in 1873. Chulalongkorn was faced with continuing Western pressure, and he maintained his father's policy of making territorial concessions to the West in the hope of retaining Siam's overall independence. In 1893, after French gunboats forced their way up the Chao Phraya River to Bangkok, he was forced to cede all Lao territories east of the Mekong River to France, and in 1907 the French took over three territories in northwestern