The Varangian Guard was an elite unit of the Byzantine Army from the tenth to the fourteenth century who served as personal bodyguards to the Byzantine emperors. The Varangian Guard was known for being primarily composed of recruits from northern Europe, including mainly Norsemen from Scandinavia but also Anglo-Saxons from England. The recruitment of distant foreigners from outside Byzantium to serve as the emperor's personal guard was pursued as a deliberate policy, as they lacked local political loyalties and could be counted upon to suppress revolts by disloyal Byzantine factions.

The Byzantine army was the primary military body of the Byzantine armed forces, serving alongside the Byzantine navy. A direct continuation of the Eastern Roman army, shaping and developing itself on the legacy of the late Hellenistic armies, it maintained a similar level of discipline, strategic prowess and organization. It was among the most effective armies of western Eurasia for much of the Middle Ages. Over time the cavalry arm became more prominent in the Byzantine army as the legion system disappeared in the early 7th century. Later reforms reflected some Germanic and Asian influences—rival forces frequently became sources of mercenary units, such as the Huns, Cumans, Alans and Turks, meeting the Empire's demand for light cavalry mercenaries. Since much of the Byzantine military focused on the strategy and skill of generals utilizing militia troops, heavy infantry were recruited from Frankish and later Varangian mercenaries.