In response to this movement, the Portuguese army inverted its dispositions and headed to the South slope of the hill. Since they were fewer than the enemy and had less ground to cover, they attained their final position very early in the afternoon. To calm the soldiers' nervousness and to improve his army's defensive position, general Nuno Álvares Pereira ordered the construction of a system of ditches, pits and caltrops. This application of typical English tactical procedures had also been used by the Portuguese in the previous battle of Atoleiros and was especially effective against cavalry (the speciality of both the Castilian and the French armies).