The Ottoman admiral Turgut Reis having conquered…
March 1563 CE
An Ottoman fleet composed of fifty galleys under the command of the renegade Hasan Corso had besieged both cities in 1556 in the Siege of Oran, but the Sultan Suleiman ordered had ordered the seige lifted and the galleys withdrawn to serve in the Eastern Mediterranean, so both Mers El Kébir and Oran remain in Spanish hands despite the poor state of their defenses.
Hasan Pasha, son of Hayreddin Barbarossa and Ottoman governor of Algiers, intends to conquer both towns to incorporate them into their territories of Algiers.
King Philip II, who is aware of Hassan's intentions, had ordered the assembly a fleet in Barcelona that would transport four thousand soldiers to reinforce the small garrisons of Oran and Mers El Kébir.
These forces, however, never reached their destination due to a storm that destroyed the fleet on October 19 off the city of Málaga.
Twenty-four of the twenty-seven galleys sunk, and a large number of sailors and soldiers, including Don Juan de Mendoza, Captain General of the Galleys of Spain, perished.
Hasan Pasha, on the orders of Suleiman, soon assembles an army of one hundred thousand men including Turks, Algerines and a large number of Janissaries. This army is supported at sea by a fleet of thirty galleys, five French carracks and fifteen small vessels under the command of Jafar Catania, governor of Tlemcen. With these forces Hassan goes to Mers El Kébir, a stronghold he considers essential to the capture of Oran.
Alonso and Martin de Córdoba had meanwhile received supplies, gunpowder, tools and a few soldiers from Málaga.
To hold together both towns in order to help each other, they had decided to construct two forts: San Miguel, located on the hill that separated Oran from Mers El Kébir, and Todos los Santos, facing the second town.