المرسى الكبير
With the defeat of the Knights of Malta and the conquest of Tripoli by the Ottoman admiral Turgut Reis in 1551, and the fall of Bougie to the governor of Algiers, Salih Reis, in 1555, Oran and Mers El Kébir were, along with the island of La Goulette, the only remaining possessions of Christendom in Barbary resisting Ottoman and Moorish piracy operating along the coasts of Naples, Sicily, and the Levant. When the Ottoman commander Hasan Corso's fleet of 50 galleys besieged both towns in the Siege of Oran in 1556, it was Sultan Suleiman's order to withdraw his galleys for use in the Eastern Mediterranean that ensured Oran and Mers El Kébir could continue under Spanish control despite being weakly defended.