From that, Thang Long witnessed big changes: from the status of being a capital 800 years ago, it became a town and then a city. The area of Thang Long was also reduced to 100 ha. The economic development situation in the first half of the 19th century was not stable. The urban development mostly focused on the East and the South. Despite not being chosen as the imperial city, Thang Long had a greatly economic and political importance. The cultural depth of Thang Long-Hanoi has been still maintained via local people’s patriotic tradition and vitality of folk cultures as well as life styles of Hanoians who are famous for their elegance.

In 1858, the French colonialists started invading Vietnam. In 1873, they attacked Hanoi Citadel for the first time. Hanoi and the entire country followed the flag of Nguyen Tri Phuong. Hanoi Citadel failed and was occupied on November 20, 1873. After the failure at Cau Giay battle on April 21, 1883, the French force landed in Hanoi for the second time. Viceroy of Tonkin Hoang Dieu commanded the fight against the French. When the French force attacked the citadel, unable to defeat them, Hoang Dieu submitted a document to Tu Duc King and committed suicide. Hanoi became a city under the French Colonialism’s concession regime.
In July, 1888, the French president issued a decree to set up Hanoi which was chaired by a maire. On October 1, 1888, the Hue court also issued a royal decree to hand over Hanoi for the French. Although the French Colonialism colluded with Hue court and dominated Vietnam, they always faced with the local people’s resistance.