The Byzantine Imperial flag is yellow with a black crowned double-headed eagle. The double-headed eagle was the symbol of the Palaiologos, the last Greek-speaking "Roman" dynasty to rule from Constantinople. Emperor Michael VIII Palaiologos recaptured Constantinople from the Crusaders in 1261, from a state based in Asia Minor; the double-headed eagle symbolized the dynasty's interests in both Asia and Europe, and was kept despite the fact that virtually all of the Asian possessions were gobbled up by the Ottomans within a generation of the recapture of the city.
The double-headed eagle was a symbol used by the Byzantine Empire and the Holy Roman Empire that has been adopted by several Eastern European nations as their national symbol to this day. The two heads of the eagle represent the dual sovereignty of the Empire (secular and religious), with the head on the left symbolizing Rome and the head on the right symbolizing Constantinople.
This unique arrangement combines the historical legacy of Byzantium with the spirituality of the Orthodox faith. This powerful image transcends the ages to define 21stCentury Christian Orthodox values depicted by the cross on the eagle's breast.
The eagle appears as a decorative motif at the court of the last Comnenoi and the Ange family (12th c.), on the ceremonial costumes of members of the imperial family but not on the emperor himself. The same is true of the courtt of the Laskaris in the empire of Nicea (1204-61). The double-headed eagle was taken back to Western Europe by two daughters of the first Latin emperor, one who struck coins in Flanders with the eagle, the other marrying into the house of Savoy and bringing the eagle in the Savoy achievement.
The single eagle remained the symbol of the Empire for several centuries after the de facto division of the Empire into an eastern and western Roman Empire following the dedication, on May 11, 330, of its eastern capital named in honour of its founder, the Emperor Constantine the Great, and the later defeat of the last of the Emperors in the West, Romulus Augustulus at Ravenna in 476.
The Symbol of the Ancient and Accepted Scottish Rite of Freemasonry of Canada is a double headed eagle, its wings displayed, ensigned of a Prussian crown, perched on a sword fessway Argent, hilt and pommel to the dexter. From the sword is draped a scroll bearing the motto “Deus Meumque Jus.”