At the time of the Christian Reconquest of the Iberian peninsula after the conquest of Lisbon (1147) possession of this region fluctuated between Muslims and Christians.

Weakly manned, the fortification of Sesimbra was initially taken by the forces of King Afonso Henriques (1112-1185) on February 21, 1165, that have carried out repairs and reinforcements in defense.

The conquest of Silves Castle in 1189 by the forces of King Sancho I (1185-1211), raised a Muslim counter-offensive that resulted not only in loss of Silves as much of the region of Alentejo, to the left bank of the Tagus river. The inhabitants of Sesimbra, alerted by Alcacer do Sal and fall sick with fever who then raging in the kingdom, left the village, which thereby was occupied and devastated by the forces of Caliph Abu Yusuf Ya’qub Almohad al-Mansur (1191).

Sancho I (1185-1211) reapossou up this village around 1200 with the help of Crusaders Northern Europe (then usually called francs), which offered land for colonization. On 15 August 1201 the sovereign granted Foral Charter to the village, determining his reconstruction of the castle “from the ground up.” This charter was confirmed by his son and successor, Alfonso II of Portugal (1211-1223).