E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Eagle (in royal banners).
It was the ensign of the ancient kings of Babylon and Persia, of the Ptolemies and Seleucids. The Romans adopted it in conjunction with other devices, but Marius made it the ensign of the legion, and confined the other devices to the cohorts. The French under the Empire assumed the same device.