Before the French invaded Viet Nam in 1858, the French government had sent many diplomats to the country to ask the Nguyen Dynasty to establish bilateral trade ties. 

Most notably, a delegation led by Baron Yves Hyacinthe Potentien de Bougainville, a naval colonel, started their trip to Viet Nam in 1824.  The purpose of the trip was to promote the image of the French flag in the Far East.  They were also to give presents and a letter written by the French King Louis XVIII to the rulers of Nam Ky (Cochinchine), which was the name of the southern region of Viet Nam during the French colonial period.   The French guests arrived on the warships Thétis and Espérance.  The 44-gun Thétis had 320 sailors on board, whilst the 20-gun Espérance had a crew of 120.  After spending nearly a year visiting other places along the way, the two ships eventually arrived in Da Nang on 12 January 1825.

A model of the Thétis on display at the Musée National de la Marine in Rochefort

Colonel Bougainville asked for permission from the Nguyen Dynasty to submit the letter to Emperor Minh Mang.  During his wait for a reply, Colonel Bougainville and some of the French crew members visited several places in Da Nang between 12 and 20 January 1825.

The local people warmly welcomed the French men, and the guests felt very comfortable buying food as well as going fishing and hunting.  The naval colonel was very impressed by grey-feathered and red-shanked douc langurs on the Son Tra Peninsula.

At that time, Da Nang was merely a village situated at the mouth of a river linked to Hoi An via what was described as ‘the world’s largest and most beautiful creek’.  According to Colonel Bougainville, and other foreign travellers at the time, this creek linked the Han River with the Co Co River, which then ran through to Hoi An.  By the early 19^th century, Da Nang had overtaken Hoi An as the central region’s largest commercial port.  A fortress, which had been built by a French engineer, was already in existence on the southern bank of the Han River.   

Da Nang emerged as one of the “do not miss” destinations for foreign travellers during their visits to Dai Nam, which was the name of Viet Nam over the 1839 - 1945 period.  The city also played an important role in ensuring the defence of the southern approaches to Hue City. 

According to the Colonel, there were 3 must-visit destinations in Da Nang.  These were the Marble Mountains, an area now known as the inner-city which includes Hai Chau District, and the Son Tra Peninsula, on which many rare animals lived.

After receiving the official letter, Emperor Minh Mang decreed that French ships could anchor at the city’s port if they strictly obeyed the regulations of An Nam, which was the former name of the central region under the management of the Nguyen Dynasty.

The two French ships left Da Nang on 17 February 1825.  After visiting the Anambas Archipelago in Indonesia, Mount Sourabaya, Sydney, Valparaiso and Rio de Janiero, the ship arrived back in Brest, France on 24 June 1826.