Byzantine flags and insignia

For most of its history, the Eastern Roman (Byzantine) Empire did not know or use heraldry in the Western European sense of permanent motifs transmitted through hereditary right. Various large aristocratic families employed certain symbols to identify themselves; the use of the cross, and of icons of Christ, the Theotokos and various saints is also attested on seals of officials, but these were often personal rather than family emblems. Likewise, various emblems (σημεῖα, sēmeia; () σημεῖον, sēmeion) were used in official occasions and for military purposes, such as banners or shields displaying various motifs such as the cross or the labarum. Despite the abundance of pre-heraldic symbols in Byzantine society from the 10th century, only through contact with the Crusaders in the 12th century (when heraldry was becoming systematized in Western Europe), and particularly following the Fourth Crusade (1202–1204) and the establishment of Frankish principalities on Byzantine soil from 1204 onwards, did heraldic uses penetrate in Byzantium. A native Byzantine heraldry began to appear in the middle and lower rungs of aristocratic families in the 14th century, coinciding with the decline of imperial authority and with the fragmentation of political power under the late Palaiologan emperors. However, it never achieved the breadth of adoption, or the systematization, of its Western analogues. The single-headed Roman imperial eagle continued to be used in Byzantium, although far more rarely. Thus "eagle-bearers" (ὀρνιθόβορας), descendants of the aquilifers of the Roman legions, are still attested in the 6th century military manual known as the Strategikon of Maurice, although it is unknown whether the standards they carried bore any resemblance to the legionary aquilae. Eagle-topped scepters were a frequent feature of consular diptychs, and appear on coins until the reign of Philippikos Bardanes (711-713). It continued in use in bas-reliefs in churches and funerary monuments until well into the 11th century, however.