 On February 13, as the 11th Airborne Division approached the fort, it encountered a strong enemy fortified sector.The sector was composed of cement pillboxes armed with .50-caliber dual-purpose machineguns which defended the entrance to the fort.Upon the realization that the pillboxes (Blockhouses) were withholding the advance of his division, Pérez took it upon himself to charge the fortifications and blast them away with grenades.