Cochinchina campaign: French Navy forces captured the Citadel of Saigon, defended by 1,000 Vietnamese soldiers of the Nguyễn dynasty.

The Cochinchina campaign was a series of military operations between 1858 and 1862, launched by a joint naval expedition force on behalf of the French Empire and the Kingdom of Spain against the Nguyễn period Vietnamese state. It was the opening conflict of the French conquest of Vietnam.

The French Navy, informally La Royale, is the maritime arm of the French Armed Forces and one of the four military service branches of France. It is among the largest and most powerful naval forces in the world recognised as being a blue-water navy. The French Navy is capable of operating globally and conducting expeditionary missions, maintaining a significant overseas presence. The French Navy is one of eight naval forces currently operating fixed-wing aircraft carriers, with its flagship Charles de Gaulle being the only nuclear-powered aircraft carrier outside the United States Navy, and one of two non-American vessels to use catapults to launch aircraft.

The Citadel of Saigon also known as the Citadel of Gia Định was a late 18th-century fortress that stood in Saigon, Vietnam from its construction in 1790 until its destruction in February 1859. The citadel was involved in two wars prior to its destruction, first when it was captured by Lê Văn Khôi in 1833 and used in a revolt against Emperor Minh Mạng, then recaptured in 1835. In 1859, it was captured following a French naval bombardment and then destroyed, as part of the colonization of southern Vietnam which became the French colony of Cochinchina.

The Nguyễn dynasty was the last Vietnamese dynasty, preceded by the Nguyễn lords and ruling unified Vietnam independently from 1802 until French protectorate in 1883. Its emperors were members of the House of Nguyễn Phúc. During its existence, the Nguyễn empire expanded into modern-day Southern Vietnam, Cambodia, and Laos through a continuation of the centuries-long Nam tiến and Siamese–Vietnamese wars. With the French conquest of Vietnam, the Nguyễn dynasty was forced to give up sovereignty over parts of Southern Vietnam to France in 1862 and 1874, and after 1883 the Nguyễn dynasty only nominally ruled the French protectorates of Annam as well as Tonkin. Backed by Imperial Japan, in 1945 the last Nguyễn emperor Bảo Đại abolished the protectorate treaty with France and proclaimed the Empire of Vietnam for a short time until 25 August 1945.