The main focus of this study is the efforts of Prince Al-Munthir Bin Mohammad in facing internal dangers in Al-Andalus, during his father's reign (238-273 H.\852-886 A.D). The study concluded that he led more than ten military campaigns against the Spanish kingdoms in the north. He achieved victory in most of them, such as the battles of Morcuera and Aybar, and was defeated in some, as in Leon and Bierzo in Asturias. His military activities contributed in reducing Spanish advance towards the south. He also fought Muladis' rebels, and his efforts succeeded in curbing them in the Toledo and Gharb Al-Andalus, while the Upper March and southern regions remained rebellious.
Keywords: Al-Munthir - Al-Andalus - Muladis - Spaniards.