French forces under Rigault de Genouilly capture Saigon, beginning the Siege of Saigon

Background. Following the execution of missionaries and diplomatic failures, Napoleon III authorized a punitive expedition in 1857. Initial operations at Tourane in 1858 failed to yield strategic success. Rigault de Genouilly rejected Tonkin options, proposing an expedition against Saigon in January 1859 due to its strategic value as a food source for Vietnamese forces.

Capture of Saigon. On 17 February 1859, French and Spanish forces broke river defences and destroyed forts along the Saigon river, capturing the city. This action inaugurated the French conquest of Vietnam. The operation was part of the broader Cochinchina campaign, marking a shift from the stalled Tourane operations to a new strategic focus on the south.

Beginning of the Siege. After the capture, a small garrison under Jauréguiberry remained. In March 1860, a Vietnamese army besieged the Franco-Spanish force. The siege lasted until February 1861, when reinforcements allowed the French to defeat the besieging forces at the Battle of Ky Hoa, raising the siege.