劉永福
The reason that Liu Yongfu was able to make such a powerful counterattack against Révillon's column was because the other two French columns failed to put serious pressure on the enemy. Coronnat's centre column failed to make contact with the Black Flags at all, while Bichot's right column succeeded in capturing the village of Trem but was then held up in front of the Black Flag defences at Quatre Colonnes. On 16 August Bichot advanced to attack Quatre Colonnes, only to find that the Black Flags had abandoned their positions during the night. The battle had been fought in pouring rain, and during the night of 15 August the Red River burst its banks and began to flood the plains between Hanoi and Phu Hoai. The flooding effectively brought the battle to an end. Neither Coronnat nor Bichot was able to make any further headway on 16 August. Coronnat's column returned to Hanoi, while Bichot contented himself with occupying Quatre Colonnes and bringing back to Hanoi a number of cannon abandoned by the Black Flags in their retreat. The French would later claim that the floods had prevented them from inflicting a major defeat upon Liu Yongfu. In fact, the flooding was a disaster for the Black Flag Army. Liu Yongfu had to abandon his entrenchments in front of the Day River and fall back behind the river, leaving behind all his material and all his wounded.