Carrillo, who was at that time furthering the siege of Vila Vicosa, was fast losing men to attrition. By June, attacks by Portuguese militias were taking a heavy toll on his lines of supply, Vila Vicosa continued to put up an unexpectedly fierce defense, and the Spanish court was demanding action. In spite of these setbacks, Carrillo continued to rely on his previous plans for the capture of Lisbon. However, when informed that Meneses's numerically inferior force was advancing on him from Estremoz, Carrillo decided to engage the Portuguese.