The Aquila Was Believed Necessary to the Success of a Legion
From 104 BC onward, each legion used an aquila (eagle) as the symbol of the unit. A gold eagle would be the standard of each unit and would be carried by an officer known as the Aquilifer. The symbol was the embodiment of the honor of the legion. If the aquila was lost in battle it was devastating to the legion that lost it. It was so devastating to the legion that quite often the legion would be disbanded afterward and would never fight together again. This was based on the belief that if the legion lost its eagle then it would never recover its old fighting spirit. The eagle was used to motivate the men.
Caesar describes an incident during the first invasion of Britain in 55 BC. The soldiers became very afraid when they came in sight of Britain. This was largely because it was an unknown territory and they did not know what to expect. Caesar saw the problem and he had a great idea. His ordered the aquilifier with the eagle onto the beach. His comrades, fearing disgrace, ‘with one accord, leapt down from the ship’ and the invasion force was soon assembled on the beach, ready to take on the Britons.
The Romans would also go to great lengths to recover aquila that were lost in battle. In the Battle of Teutoburg, three legions were completely defeated and their aquila taken. Emperor Augustus waged war in retaliation against the Germanic tribes and to recover lost territory. Numerous raids of tribes, even against the coming of winter, ended with the recovery of two of the missing aquila. The battle continued for the territory and the remaining aquila but it was never recovered and the Romans never recovered their Germanic territories.