In Merovingian society, the military was important not only as a means for defense but also as a political tool to maintain and expand royal power. It was strongly integrated into society, as every man of a certain age and constitution was a potential fighter, while a main function of the highest social stratum was military leadership. This chapter discusses the origins, nature, and role of the Frankish military by taking a close look at the sources and current research on the subject. It deals with questions related to military professionalism, recruitment, organization, and command, and discusses the ongoing process of militarization that characterized not only the increasingly powerful Frankish elite but also the local population and society as a whole.