Algiers had been under the control of the Ottoman Emperor Suleiman the Magnificent since its capture in 1529 by Barbarossa. Barbarossa had left Algiers in 1535 to be named High Admiral of the Ottoman Empire in Constantinople, and has been replaced as Governor by Hassan Agha, an eunuch and Sardinian renegade.

Hassan has in his service the well-known Ottoman naval commanders Dragut, Sālih Reïs and Sinān Pasha.

Charles V makes considerable preparations for the expedition, wishing to obtain revenge for the recent siege of Buda; however the Spanish fleet is severely damaged by a storm, forcing him to abandon the venture.

Charles V embarks very late in the season, on September 28, 1541, delayed by troubles in Germany and Flanders. The fleet is assembled in the Bay of Palma, at Majorca. It has more than ffve hundred sails and twenty-four thousand soldiers.

After enduring difficult weather, the fleet only arrives in front of Algiers on October 19. The most distinguished Spanish commanders accompany Charles V on this expedition, including Hernán Cortés, the fifty-six-year-old conqueror of Mexico, though he is never invited to the War Council.

Troops are disembarked on October 23, and Charles establishes his headquarters on a land promontory surrounded by German troops.

German, Spanish, and Italian troops, accompanied by one hundred and fifty knights of Malta, begin to land while repelling Algerine opposition, soon surrounding the city, except for the northern part.

The fate of the city seems to be sealed; however, the following day the weather becomes severe with heavy rains.

Many galleys lose their anchors and fifteen are wrecked onshore. Another thirty-three carracks sink, while many more are dispersed.

As more troops are attempting to land, the Algerines start to make sorties, slaughtering the newly arrived.

Charles V is surrounded, and is only saved by the resistance of the Knights of Malta.
Losses among he invading force are heavy with seventeen galleys and one hundred and thirty carracks lost, plus large numbers of sailors and soldiers.

A Turkish chronicler confirms that the Berber tribes were massacring the twelve thousand men men of the invading forces.