War and peace: hired troops and military aid in Byzantine and English treaties, c.900–1200

Abstract The rulers of Byzantium and England are well known for their centralized nature and their active approach to diplomacy. Both powers often utilized treaties to bolster their military forces, and to undermine those of their foes. Of course, allegiance was not always clear-cut, with many powers having complex relations with their neighbours and the treaties catering to the conflicting obligations of those involved. This article focuses on the treaties of two of the most bureaucratic powers of the medieval world who have comparable treaty corpuses, utilizing the theme of military service to show that treaties were primarily pragmatic documents.