 Complete the following phrase:  From the time of Marius consul 107 BC, the standard of all legions was the aquila eagle. The pole was surmounted by a sculpted eagle of solid gold, or at least gold-plated silver, carrying thunderbolts in its claws representing Jupiter, the highest Roman god. Otherwise the pole was unadorned. No exemplar of a legionary eagle has ever been found doubtless because any found in later centuries were melted down for their gold content. The eagle was borne by the aquilifer, the legions most senior standard-bearer. So important were legionary eagles as symbols of Roman military prestige and power, that the imperial government would go to extraordinary lengths to recover those captured by the enemy. This would include launching full-scale invasions of the enemys territory, sometimes decades after the eagles had been lost e.g. the expedition in 28 BC by Marcus Licinius Crassus against Genucla Isaccea, near modern Tulcea, Rom., in the Danube delta region, a fortress of the Getae, to recover standards lost 33 years earlier by Gaius Antonius, an earlier proconsul of Macedonia. Or the campaigns of AD 1417 to recover the three eagles lost by Varus in AD 6 in the 