Stone projectiles from the siege of Alcala la Vieja (Spain) and likely trebuchet placement

Investigations of the siege of Islamic Alcala la Vieja (Madrid, Spain) by Christian forces in the 12th century ce have depended on secondary sources proven to be unreliable and error-laden. In a search for possible locations of trebuchets used by the Christian attackers, the option was for an interdisciplinary approach combining elements from archaeology, physics and spatial analysis. The discovery of stone projectiles near the Islamic fortress allowed for the application of projectile physics to the calculation of several effective firing ranges for each stone. Those outcomes, in combination with geographical information system (GIS) data, have revealed a possible location where Christian forces could have effectively deployed hybrid trebuchets as siege engines.