Abstract
The research aims to shed light on the nature of the army in the late Abbasid eras , especially after the rise of the Buyids and the Seljuks and their conficating the powers of the Abbasid caliphs and subjecting the Caliphate under them. This led also to the internal strifes and revolts and the army’s preoccupation with suppressing them and their impact on military campaigns and protection of the borders of the Muslim state facing the traditional enemy Byzantium . As well as shedding light on the most important measures taken by the Caliphs in order to confront the increase and domination of foreign elements, especially with regard to the institution of the army .
