Having crept his force up along the right bank of the Fluvià and set up headquarters at La Armentera, a village near the river's mouth on the Mediterranean Sea, General Lazán prepared a coup de main against the French battalion installed atop Castelló d'Empúries. Since bad roads precluded a night attack, Lazán moved in the early morning, brusquely forcing the French off the ridge. While Reille's troops effected a disciplined fighting withdrawal toward Rosas, the Chasseurs de Juan Clarós, acting as the vanguard for General Castro's division, circled across their path of retreat and set up a position in a grove next to the main road, preparing to block the French passage. Caught in the pincers, the French were cut down. Only 80 escaped unwounded and 90 surrendered.
When Reille, established at Figueras, learned of the rout of his men, he set out against the Spaniards the next day with 3,000 infantry and cavalry, aiming to cut their communications with Gerona. In spite of the rapid French movements, Reille was unable to achieve a surprise, and Lazán awaited him with his men solidly entrenched at Castellón. Seeing his attacks repulsed everywhere along the line, Reille decided not to try conclusions with the Spaniards, and Lazán fell back on Gerona unmolested.