Explorer, Oriental scholar and diplomat, Pierre Lefèvre-Pontalis (1864-1938) was a member of Pavie Mission to Laos in the 1890s, participating in drawing up the borders between French Indochina and independent Siam, as well as the French territories and Burma, annexed by the British in 1886. He was later appointed as Minister Plenipotentiary to Siam. However, before taking up this ambassadorial role he journeyed in Siam and Burma in 1912, during which he wrote copious notes recording ethnographic, historical and geopolitical thoughts. This is the first time these journals have been published and provides a unique window into the colonial mindset of the time.