In the early hours of July 5, 1885, imperial troops under regent Ton That Thuyet launched a surprise assault on the French garrison at Mang Ca and the Residency in Hue. The attack failed; French forces counterattacked swiftly and seized the entire citadel within hours.
Emperor Ham Nghi and Ton That Thuyet fled the capital to Tan So in Quang Tri province. From exile, the king issued the Can Vuong (Save the King) edict, calling on scholars and citizens across the country to take up arms against the French — igniting a widespread armed resistance movement that lasted until the end of the nineteenth century.
The fall of the capital marked the effective end of Nguyen dynasty independence and the beginning of full French colonial rule. Though physically occupied, the Hue Citadel remained a powerful symbol of Vietnamese identity and the struggle for sovereignty.