 In February 1476, the Portuguese army, reinforced by troops brought by John II of Portugal, son of Afonso V, left its base in Toro and surrounded Ferdinand in Zamora.The siege took a worse toll on the Portuguese than on those under siege because of the Castilian winter, and on March 1, Afonso V withdrew back towards Toro.Ferdinand and his troops launched a pursuit and caught up to the Portuguese one league (about 5 km) from Toro, and combat began.