For G. Marcais, "the Ottoman accession greatly alarmed the Spaniards." cause Spain had grat pretentions of domination in the Mediterranean region and to which the Turks ended with the eradication of the Penon in 1529. The situation of Algiers in the 1516 showed the advance of the Sublime Porte and the Spanish anxiety was all the more More justified than that it was. Muslims who came to the aid of other Muslims "against the oppression of Christianity" as the aggressions it was subjected to did not stopped.. El Djazair developed its own dimensions and its city status (Dar el Jihad), as well as maritimes activities.
This more organized activity made algiers as well as the powerful city in the Mediterranean, as a rich city that will attract so many people. For all these reasons, which are not only of a religious nature, the Christian countries organized very important attempts to conquer the city. under economic objectives, as said by C.A Julien: "the main aim was the conquest by economic colonization and not the reasons for crusades." These crusades attempts could only perpetuate the warlike character of the city during the entire Turkish period. Besides, from all that evenments one of the forts of the city (or door) was baptized"Bab el jihad". Algiers thus became a citadel, and was then rightly described as the"well guarded."