Detailed coastal chart of the Southern Coastline of China and the Coast of Vietnam, south to the Da Nang area, published in Paris by the French Depot de la Marine.
The chart was apparently used in the 1870s, shortly after French obtained Territorial control over the regions of Cochinchina (Vietnam), shown on the chart.
The annotations in the area of Hai Phong show the attempts to significantly improved the known hydrographical and geographical information in the region, which was still not well understood by the French. There are two groups of annotations, executed in a contemporary French hand.
To the south, the annotations illustrate newly understood details around the several French Missions in the area, including a note regarding a Route of Foreigners. Further south, the area around Hai Phong and its rivers are better charted, inland to Kei-cho and Bac-ninh. This may relate to the French study of the dikes, canals and flooding in this region, which was the subject of considerable study by French Engineers and Administrators in this time period, due to the constant flooding.
The chart was created during the early years of France's involvement the region. France was heavily involved in Vietnam in the 19th Century, protecting the work of the Paris Foreign Missions Society in the country was often presented as a justification. In 1858, the brief period of unification under the Nguyễn dynasty ended with a successful attack on Da Nang by French Admiral Charles Rigault de Genouilly under the orders of Napoleon III. Genouilly's mission was to stop attempts to expel Catholic missionaries. His orders were to stop the persecution of missionaries and assure the unimpeded propagation of the faith.
In September 1858, fourteen French gunships, 3,000 men and 300 Filipino troops provided by the Spanish attacked the port of Tourane (present day Da Nang), causing significant damage and occupying the city. After a few months, Rigault had to leave the city due to supply issues and illnesses. Sailing south, de Genouilly then captured Saigon in February 1859.
On April 13, 1862, the Vietnamese government was forced to cede the three provinces of Biên Hòa, Gia Định and Định Tường to France. De Genouilly was criticized for his actions and was replaced by Admiral Page in November 1859, with instructions to obtain a treaty protecting the Catholic faith in Vietnam, but refrain from territorial gains.
French policy four years later saw a reversal, with the French continuing to accumulate territory. In 1862, France obtained concessions from Emperor Tự Đức, ceding three treaty ports in Annam and Tonkin, and all of Cochinchina, the latter being formally declared a French territory in 1864. In 1867, the provinces of Châu Đốc, Hà Tiên and Vĩnh Long were added to French-controlled territory.
In 1863, the Cambodian king Norodom had requested the establishment of a French protectorate over his country. In 1867, Siam (modern Thailand) renounced suzerainty over Cambodia and officially recognized the 1863 French protectorate on Cambodia, in exchange for the control of Battambang and Siem Reap provinces which officially became part of Thailand. These provinces would be ceded back to Cambodia by a border treaty between France and Siam in 1906.