The Spanish presence in Algeria is considered a movement of extremist ideologies in the modern era, as it originated from a religious bias to achieve its goals in Algeria. Consequently, it planned to eradicate everything Arab and Islamic in the Maghreb region, replacing it with Spanish Crusader thought and beliefs. This became evident in the elimination of the Islamic resistance movement in the Maghreb region, the imposition of treaties on some rulers of emirates and tribes, as well as the conversion of mosques into churches, the construction of bishoprics, and the raising of crosses in the areas under its control. This makes it one of the prominent extremist ideological movements that Algeria witnessed in the early modern era. This study is included within the scope of historical studies on the most prominent extremist ideological movements in the Maghreb region in the modern era.

Extremist ideological movement, Crusader bias, Algerian resistance, Spanish belief, treaties.