Two aspects of the Byzantine military organization in 626-628 AD were considered: the role and status of Armenian ethnic units within the Byzantine army and the measures of Emperor Heraclius for reestablishment the Byzantine defense system in the Near East in 628 AD, after the victory over the Persians. Based on a series of narrative sources (both Greek and Armenian ones; the Armenian sources were translated into the West European and Russian languages) and also inscriptions commemorating the powerful representatives of the Armenian noble family (naχarars), the evolution of the relations between Byzantium and Armenian aristocracy was considered. The features of Byzantine administrative policy within the territory of Armenian provinces during Heraclius’ campaign against the Persians were distinguished. It was concluded that Heraclius modified the retinues of Armenian naχarars composed of local inhabitants of Armenian provinces in regular military detachments in 626-628 AD and included them in his field army, which battled against the Persians. However, the naχarars’ retinues continued to be under command of their native Armenian nobles that were the leaders of powerful houses and families. Many Armenian naχarars were granted court titles and even high-ranking administrative offices by Heraclius. At the same time, it was proved that in 628 AD, after the victory over the Persians, Heraclius reestablished the old military-administrative government institutes, which managed the Byzantine Near East previously, i.e., the office of master of soldiers in the East (the supreme commander of Byzantine field army within this region) and praetorian prefect of the East (the chief of the civil power at the Near East provinces).