Task: Question Generation
Input (English): Passage: In February 1479, a Portuguese army commanded by Garcia de Meneses, Bishop of Évora, penetrated into Extremadura. His objective was to occupy and reinforce the strongholds of Mérida and Medellín, controlled by Beatriz Pacheco, Countess of Medellin and supporter of Afonso V. According to Palencia, the Portuguese army was composed of about 1,000 Knights , plus infantry. 180 Knights of the Order of Santiago marched alongside him, commanded by their treasurer, Alfonso de Monroy. On February 24, near the hill of Albuera, the army was challenged by Isabellian forces commanded by Alonso de Cárdenas, Master of the Order of Santiago. The army consisted of 500 Knights of the Order, 400 Knights of the Hermandad , and 100 infantrymen. The battle was heavily contested. The Isabellian infantry suffered a severe blow from the Juanist cavalry and became disorganized, but intervention by the Master of Santiago aided the panicked infantry. The Portuguese were forced to retreat, leaving significant spoils of war on the battlefield, as well as around 85 dead Knights. Only 15 Isabellian Knights were killed. The bulk of the Portuguese army was able to take refuge in Mérida and from there continued its march to Medellín, which they occupied. Supporters of King Ferdinand placed Medellín and Mérida under siege.
Output (English): Approximately how many Portuguese knights were killed?