On 24 and 25 February, 1861 Admiral Léonard Charner relieved the Siege of Saigon by defeating the besieging Vietnamese army in the battle of Ky Hoa.

Believing that he had broken Vietnamese resistance with his victories at Ky Hoa and Mỹ Tho, he asked to return to France in the summer of 1861.

A fortnight after his arrival in Saigon, after receiving an unsatisfactory response to an ultimatum he had sent to the Vietnamese governor Nguyen Ba Nghi, he mounted a major campaign to occupy the province of Biên Hòa.

They had built an entrenched camp held by 3,000 men at My Hoa, midway between Biên Hòa and Saigon, and obstructed the course of the Donnai with nine solid barrages and a stockade.

Finally, a flotilla of armed launches, having followed the creeks as far as Rach Gò Công, cannonnaded the works which were also bombarding the gunboats anchored in the Donnai under the orders of lieutenant de vaisseau Harel of Avalanche.

The marine infantry attacked the enemy's centre, while the chasseurs menaced his right and the Spaniards his left, and the cavalry made a turning movement to cut off his retreat.

On 16 December the troops crossed the Donnai and occupied Biên Hòa, which the Annamese soldiers had evacuated, but not before burning alive numerous Christian prisoners.