France significantly increased its diplomatic and military activism in Asia during the Second Empire, after a century-long pause following its decisive defeat by Great Britain during the Seven Years' War. It joined the UK and participated in the Second Opium War between 1856 and 1860, including the looting of the Old Summer Palace and Summer Palace in Beijing in October 1860. Also in 1856, Napoleon III sent Charles de Montigny on an embassy to King Mongkut of the Rattanakosin Kingdom of Siam, reviving high-level diplomatic contacts that had flourished at the time of Louis XIV and King Narai of the Ayutthaya Kingdom during the 1680s. In 1858, Napoleon III's representatives concluded the Treaty of Amity and Commerce between France and Japan, and separately the French military started the Cochinchina campaign, establishing a foothold in what is now Southern Vietnam. In 1863, France went on to establish a protectorate in Cambodia, and in 1866 it launched its ill-fated expedition to Korea. In 1867 the Exposition Universelle would trigger a fashion and artistic frenzy for "Japonisme".