Siege of Lisbon The Siege of Lisbon , from July 1 to October 25 , 1147 , was the military action that brought the city of Lisbon under definitive Portuguese control and expelled its Moorish overlords . The Siege of Lisbon was one of the few Christian victories of the Second Crusade — it was " the only success of the universal operation undertaken by the pilgrim army , " i . e . the Second Crusade , according to the contemporary historian Helmold — and is seen as a pivotal battle of the wider " Reconquista " . The Fall of Edessa in 1144 led to a call for a new crusade by Pope Eugene III in 1145 and 1146 . In the spring of 1147 , the Pope authorized the crusade in the Iberian peninsula . He also authorized Alfonso VII of León and Castile to equate his campaigns against the Moors with the rest of the Second Crusade . In May 1147 , the first contingents of crusaders left from Dartmouth in England for the Holy Land . Bad weather forced the ships to stop on the Portuguese coast , at the northern city of Porto on June 16 , 1147 . There they were convinced to meet with King Afonso I of Portugal . The crusaders agreed to help the King attack Lisbon , with a solemn agreement that offered to the crusaders the pillage of the city ' s goods and the ransom money for expected prisoners . The siege began on July 1 . After four months , the Moorish rulers agreed to surrender on October 24 , primarily because of hunger within the city . Most of the crusaders settled in the newly captured city , but some of the crusaders set sail and continued to the Holy Land . Lisbon eventually became capital city of the Kingdom of Portugal , in 1255 . Second Crusade . The traditional start of the Reconquista is identified with the defeat of the Muslims in the Battle of Covadonga in 722 . After the First Crusade in 1095 - 1099 , Pope Paschal II urged Iberian crusaders ( Portuguese , Castilians , Leonese , Aragonese , and others ) to remain at home , where their own warfare was considered just as worthy as that of crusaders travelling to Jerusalem . The Fall of Edessa in 1144 led to a call for a new crusade by Pope Eugene III in 1145 and 1146 . In the spring of 1147 , the Pope also authorized a crusade in the Iberian peninsula , where " the war against the Moors had been going on for hundreds of years . " Eugene encouraged Marseilles , Pisa , Genoa , and other Mediterranean cities to fight in Iberia . He also authorized Alfonso VII of León and Castile to equate his campaigns against the Moors with the rest of the Second Crusade . On May 19 , 1147 , the first contingents of crusaders left from Dartmouth in England , consisting of Flemish , Frisian , Norman , English , and Scottish crusaders , and some from Cologne , who collectively considered themselves " Franks " . No prince or king led this part of the crusade , England at the time being in the midst of The Anarchy . The fleet was commanded by Henry Glanville , Constable of Suffolk . Other crusader captains included Arnold III of Aerschot , Christian of Ghistelles , Simon of Dover , Andrew of London , and Saher of Archelle . Redirected efforts . According to Odo of Deuil there were 164 ships bound for the Holy Land , and there may have been as many as 200 by the time they reached the Iberian shore . Bad weather forced the ships to stop on the Portuguese coast , at the northern city of Porto on June 16 , 1147 . There they were convinced by the bishop , Pedro II Pitões , to meet with King Afonso of Portugal . The king , who had reached the Tagus River and conquered Santarém in 15 March , had also been negotiating with the pope for the recognition of his title of King . He was notified of the arrival of a first party and hastened to meet them . The undisciplined multi - national group agreed to help him there , with a solemn agreement that offered to the crusaders the pillage of the city ' s goods and the ransom money for expected prisoners . For the city , " they shall have it and hold it until it has been searched and despoiled , both of prisoners for ransom and of everything else . Then , when it has been as thoroughly searched as they wish , they shall turn it over to me . . . " Afonso promised to divide the conquered territories as fiefs among the leaders . He reserved the power of " advocatus " and released those who were at the siege and their heirs trading in Portugal from the commercial tax called the " pedicata " . The English crusaders were at first unenthusiastic , but Henry Glanville convinced them to participate . Hostages were exchanged as sureties for the oaths . Fall of Lisbon . The siege began on July 1 . The Christians soon captured the surrounding territories and besieged the walls of Lisbon itself . After four months , the Moorish rulers agreed to surrender ( October 21 ) , because the Crusaders ' siege tower reached their wall ( thus causing a one day standstill ) and because of hunger within the city , which was sheltering populations displaced from Santarém as well as " the leading citizens of Sintra , Almada , and Palmela . " After a brief riotous insurrection the Anglo - Norman chronicler attributes to " the men of Cologne and the Flemings " , the city was entered by the Christian conquerors , on October 25 . The terms of the surrender indicated that the Muslim garrison of the city would be allowed to keep their lives and property , but as soon as the Christians entered the city these terms were broken . According to the " De expugnatione Lyxbonensi " , Aftermath . Some of the crusaders set sail and continued to the Holy Land . However , most of the crusaders settled in the newly captured city , thus boosting the number of Christian supporters in Iberia . Gilbert of Hastings was elected bishop . This is seen as the beginning of the historic relationship between England and Portugal which would later form the Anglo - Portuguese Alliance . In spite of the contractual nature of the city ' s surrender , a legend arose that the brave Portuguese warrior and nobleman , Martim Moniz , sacrificed himself in order to keep the city doors open to the conquering Christian armies . Lisbon eventually became the capital city of the Kingdom of Portugal in 1255 . The victory was a turning - point in the history of Portugal and the wider Reconquista , which would be completed in 1492 .