On 10 March 1147, King Afonso I of Portugal departed from Coimbra with 250 of his best knights intending to capture the Moorish city of Santarém, a goal that he had previously failed to achieve. The conquest of Santarém was of vital importance to Afonso's strategy; its possession would mean the end of the frequent Moorish attacks on Leiria and would also allow a future attack on Lisbon.

The Conquest of Santarém took place when the troops of the Kingdom of Portugal under the leadership of Afonso I of Portugal captured the Almoravid city of Santarém.