Key Facts
- Start date
- 30 July 1217
- End date
- 18 October 1217
- Duration
- ~2.5 months
- Crusade context
- Part of the Fifth Crusade
- Crusader origin
- Mainly Rhineland and Low Countries
Strategic Narrative Overview
The siege began on 30 July 1217 and combined the forces of Portugal, León, the military orders, and the crusading fleet led by Count William I of Holland. The crusaders had not received explicit papal authorisation to divert from the main crusading theatre, but joined the effort regardless. Over nearly three months, the allied besiegers maintained pressure on the Almohad garrison until the city's defences were overcome.
01 / The Origins
Alcácer do Sal was a well-fortified frontier outpost of the Almohad Caliphate that regularly launched raids into the diocese of Lisbon. Bishop Soeiro II of Lisbon, whose territory was directly threatened by these incursions, conceived the expedition to neutralise the threat. The operation drew together Portuguese and Leonese forces, military orders, and crusaders from the Rhineland and Low Countries who were en route to the Holy Land as part of the Fifth Crusade.
03 / The Outcome
Alcácer do Sal capitulated on 18 October 1217 and was incorporated into the Kingdom of Portugal under King Afonso II, who had not participated in person. Following the victory, the crusaders were ordered by Church authorities to proceed to the Holy Land as originally mandated. The conquest removed a persistent raiding base and extended Portuguese control further south along the Tagus and Sado river valleys.
Belligerents & Mobilization Analysis
Side A
4 belligerents
William I, Count of Holland, Bishop Soeiro II of Lisbon, Afonso II of Portugal.
Side B
1 belligerent
Kinetic Engagement Axis
Scroll horizontally to view full axis. Events plotted relatively.