The western basin of the Mediterranean formed a collision zone between the Islamic and Crusader forces, and the importance of the region and its challenges increased after the emergence of the ambitions of the King of Aragon Ferdinand and his wife Isabella, Queen of Castile, and the declaration of their crusader war against the Muslim lands in Islamic Morocco, and the coasts of Algeria were subjected to repeated attacks, and faced difficulties The internal situation of Algeria and the inability to face these challenges was the result of the appeal of its population to the Ottoman Empire for what it represented as a protector of Muslims and the standard-bearer of the Islamic Caliphate. And here began a decisive stage in Algeria's modern history.