The initiative of starting the battle was with the Castilian side. The French allied heavy cavalry charged in full strength, in order to disrupt order in the enemy lines. Even before they could get into contact with the Portuguese infantry, however, they were already disorganized. Just as at Crécy, the defending archers and crossbowmen, along with the ditches and pits, did most of the work. The losses of the cavalry were heavy and the effect of its attack completely null. Support from the Castilian rear was late to come and the knights that did not perish in the combat were made prisoners and sent to the Portuguese rear.