Battle of Alcácer do Sal (1161)
The Battle of Alcácer do Sal in 1161 was an armed encounter between the troops of King Afonso Henriques and the Almohads commanded by Abu Mohammed Abdallah Ben Hafs, known to the Portuguese as Benafece.

After conquering the eastern Maghreb, the Almohad caliph Abd al-Mu'min decided to intervene in the Iberian peninsula to unite the Muslim states under his authority, by force if necessary, and prevent the advance of the Christian kingdoms. In the early months of 1160, the Caliph ordered the Wali of Granada to restore and improve the fortifications of Gibraltar and, once these were completed, Abd al-Mu'min crossed the strait at the head of a large army of 18,000 men and settled in the city.Henry Morse Stephens, p. 55Alexandre Herculano, p. 397 Informed of the conquests of Afonso Henriques or Ibn Errik, who had recently conquered Alcácer do Sal in 1158, among other settlements in the Alentejo interior, the Caliph sent a detachment under the command of Abu Mohammed Abdallah Ben Hafs or Benafece to the west to recover them.Alexandre Herculano, p. 397

When they entered the territory of Alcácer do Sal, King Afonso Henriques summoned his troops and took to the field to confront the Muslims. However, the Portuguese were unsuccessful against such a large enemy and were defeated in a pitched battle. More than 6,000 Portuguese died and a large number of combatants were captured.Alexandre Herculano, p. 397

As a result of this battle, the Portuguese lost a large number of settlements they had recently conquered in the Alentejo to the Almohads.Alexandre Herculano, p. 397 Beja, conquered by the Portuguese in December of the previous year, was abandoned and reoccupied by the Muslims. Alcácer do Sal, however, remained in Portuguese hands, as a bastion of Christian defense.S. Lay, p. 127 The Muslims did not advance further north and after the successful campaign, Benafece withdrew when the Caliph ordered him to return to base; the following year, Abd al-Mu'min returned to North Africa and, in December, the Portuguese resumed the war against the Muslims of Andalus, beginning with an attack by the Santarém militia against Beja, led by Fernão Gonçalves.Alexandre Herculano, p. 397S. Lay, p. 127
References

Category:Battles of the Reconquista
Category:Battles involving Portugal
Category:Battles involving Morocco
Category:Battles involving the Almohad Caliphate
Category:Conflicts in 1161
Category:12th century in Portugal
Sources
Henry Morse Stephens (1895) The Story of Portugal.

Alexandre Herculano (1846) História de Portugal, volume I.

S. Lay (2009) The Reconquest Kings of Portugal.