France gained a foothold on what is now known as “French Indochina” in the 1860s. Cochinchina (Southern Vietnam) ceded its three provinces to the French, while Cambodia agreed to become a protectorate of the French Empire in order to defend itself against neighbouring Siam. Meanwhile, British-controlled Shanghai was a booming economic trading port thanks to its location at the mouth of the Yangtze River. Seeking to emulate Shanghai’s financial success, French colonial officers voted to launch an expedition “into the unknown lands north of the Mekong Delta” to make Saigon a significant port for trading along a sizeable inland waterway. Captain Ernest Doudard de Lagrée and Louis Marie Joseph Delaporte were the first Europeans to fully traverse the mighty Mekong River up through the six countries it flows through (China, Myanmar, Laos, Thailand, Cambodia and Vietnam) in order to assess the navigability of the river. They also sought to create a commercial route linking Saigon to both the Siamese Empire and southern China. When Doudard de Lagrée and his small expedition departed Saigon in June of 1866, Southeast Asia’s largest river was still largely unexplored; its peoples and source were still mysterious to the world. Shortly after leaving Phnom Penh, however, the explorers discovered why there were never any southbound vessels coming from Laos on the Mekong River. At the border of Cambodia and Laos lies Khone Falls, where “Four Thousand Islands” split the Mekong into countless smaller channels, all with rapids and waterfalls untraversable by trading vessels. Undeterred, de Lagrée was forced to abandon their large steamboat at the rapids and board smaller vessels upstream. Although the expedition now realised that their primary goal of establishing a trading network along the river was unfeasible, they still intended to document remote settlements and map the undiscovered. After this point, de Lagrée’s team progressed sluggishly, resting or exploring connecting waterways and regions around towns that dot the upper Mekong’s riverbanks. The expedition would continue its journey to the origin of the majestic Mekong River in China’s Yunnan province before taking an overland route to Shanghai. Although the voyage revealed that Saigon was not a viable river port, the First French Mekong Expedition redeemed itself with an accidental discovery while heading eastward and descending upon a deep river valley. They deduced that this mighty river was most likely the Red River, which flows downstream through Hanoi and into the Gulf of Tonkin. Unlike the Mekong, the Red River was open to trading vessels — this was the inland river trading route between Vietnam and China they had been seeking all along. Sadly, in March 1868, twenty-one months after embarking from Saigon, Captain Ernest Doudard de Lagrée succumbed to dysentery and infected wounds during the final trek to Shanghai. His body was buried in Dongchuan, China. Captain Francis Garnier, with the remainder of Doudard de Lagrée’s expedition team, took over the mission and would reach Shanghai and sail back to Saigon, finally succeeding in June 1868. We honour this courageous expedition and men with their exploratory contributions to Southeast Asia.