Battle of Issus
The allusions from Classical Antiquity included in the speech are to the Sacred Band of Thebes and the Persian Immortals—elite units of, respectively, the city state of Thebes and the Achaemenid Kings of Persia; and to the Battle of Issus where Alexander the Great decisively defeated the latter. (In fact, though Acre was not conquered, Napoleon's Imperial Guard did come to be informally called "The Immortals.")