Battle of Hanoi
1946 CE.
Shown on the map at 21.033°, 105.850°.
On December 19, 1946, Viet Minh soldiers detonated explosives in Hanoi, and the ensuing battle, known as the Battle of Hanoi marked the opening salvo of the First Indochina War.
Text from the Wikipedia article Battle of Hanoi (1946), licensed CC BY-SA 4.0.