midnight
Almost at the same moment , one of the regiments of the 4th division were suddenly charged by 1200 French soldiers , hidden behind a declivity , and driven back with heavy loss . For a moment , it seemed that the fate of the battle might yet be changed ; but Wellington had the strongest reserve , the sixth division was brought up and , though the French fought obstinately , Clausel was obliged to abandon the Hermanito ; and the army began to fall back , the movement being covered by their guns and the gallant charges of their cavalry . The whole of the British reserves were now brought into action , and hotly pressed them ; but , for the most part maintaining their order , the French fell back into the woods and , favoured by the darkness , and nobly covered by Maucune , who had been strongly reinforced , they drew off with comparatively little loss , thanks to the Spaniards ' abandonment of the fort guarding the ford at Alba . Believing that the French must make for the ford of Huerta , Wellington had greatly strengthened his force on that side and , after a long march to the ford , was bitterly disappointed , on arriving there at midnight , to find that there was no sign of the enemy ; although it was not until morning that he learned that they had passed unmolested over the ford of Alba . Had it not been for the Spanish disobedience and folly , Marmont 's whole army would have had no resource but to surrender . Marmont 's strength when the fight began was 42,000 infantry and cavalry , and 74 guns . Wellington had 46,000 infantry and cavalry , and 60 pieces ; but this included a considerable Spanish force and one of their batteries , and 10,000 Portuguese who , however , could not be reckoned as good troops .