A siege undertaken as part of the Second Crusade (1147-1149) by Afonso I Henriques, king of Portugal, and a fleet of northern crusaders en route to the Holy Land, resulting in the capture of Lisbon (Port. Lisboa) from its Muslim inhabitants on 24 October 1147. The principal source of information for the siege, De expugnationeLyxbonensi, is an eyewitness account apparently composed by an Anglo-Norman priest named Raol.
A league of Anglo-Norman, Flemish, and German crusaders sailed from Dartmouth on 19 May 1147 and put ashore at Oporto in Portugal on 16 June before proceeding to Lisbon, where a meeting was arranged with King Afonso. The king, who had unsuccessfully attacked Lisbon with the assistance of English ships around five years earlier, was apparently anticipating the fleet’s arrival. There are also indications that during the planning for the assault the Portuguese ruler had been in contact with Bernard of Clairvaux, a key figure in the organization of the crusade. In return for the spoils of the city and the chance to fulfill their Christian duty, the fleet’s representatives agreed to assist Afonso in his attack on Lisbon, which commenced on 1 July 1147.
Following an arduous siege, Lisbon surrendered to King Afonso on 24 October. A brutal sack of the city ensued, which the chronicler Raol blamed on the German troops. Subsequently, some members of the northern expedition remained in Portugal while others proceeded to assist in the combined Spanish-Genoese siege of Tortosa or continued on to the Holy Land. Contemporary Christians generally recognized the capture of Lisbon as one of the few military successes of the Second Crusade, a judgment frequently echoed by modern historians, who have increasingly emphasized the place of the Portuguese assault within the period’s overall crusading activity.