 In August in response to the death of the Vietnamese emperor Tự Đức and a consequent succession crisis, the French government approved an operation to coerce the Vietnamese court at Huế.On 18 August Courbet's naval division bombarded the Thuận An forts at the entrance to the River of Perfumes, and on 20 August, in the Battle of Thuận An, a landing force of sailors and marine infantry overran the Vietnamese defences and captured the forts.Courbet's victory, which enabled the French to occupy Huế whenever they wanted, compelled the Vietnamese court to submit to French authority and sign the Treaty of Huế, which recognised the French protectorate in Tonkin.