The spiritual center of a Roman military camp was the »sacellum,« a space consecrated to the flags of the legion in which the army standards (insignia) were stored. On special holidays, the army standards were anointed, decorated with laurel and garlands, as well as adorned with bands. One of these holidays was the »dies natalis aquilae,« the »birthday« of the (legionary) eagle, the day on which the soldiers celebrated the anniversary of the legion’s founding. The army standards were symbols and warrantors for religious commitment to the state as well as for military virtues and successes. Therefore, the army standards were ritually worshipped as representatives of military religion (»religio castrensis«).
Consequently, losing the army standards was the ultimate disaster that could happen to a legion, and everything in their power needed to be done to regain them. For example, after Emperor Augustus had succeeded in regaining the legionary eagle which Crassus had lost in 53 BC to the Parthians, this event was celebrated by the minting of special coins.
The Roman army standards also exerted a strong psychological influence on the soldiers, who would gather around them before a battle and during lulls. They always had the standards’ protection on their minds when following the standard bearer into battle. Thus the army standards were literally both a guiding motif and motive; a point of reference as well as a symbol of the troops’ morale. The Latin language knows numerous military terms that refer to the army standards, for example »singa tollere,« »lifting the army standards,« which means »to break camp,« or »signa movere,« (»moving the army standards«) for marching off, and many more.
The divisions of the Roman army had different types of army standards, either a standard called »signum« or a flag named »vexillum« in Latin. Originally, a unit had one of the following five creatures as an insignia: eagle, wolf, minotaur, horse and boar. The eagle (»aquila«) finally became the insignia of the legions. Later, zodiac signs were used as insignia of the legions, which were used as often as the »imagines«. The latter were busts of either the Emperor or of other members of the imperial house.
The use of the various army standards was governed by regulations and often changed in the course of a multitude of military reforms. The »signa« were used for tactical purposes in battle. 30 signa existed in a legion, because each of the three maniples in a century had its own signa.
The »primipilus« was the highest ranking centurion and leader of the first cohort. He watched over of the »aquila,« the eagle-shaped legion standard, which was their religiously worshipped symbol. The eagle was initially made of silver using the repoussé technique and then gold-plated. Later, the aquila was made of pure gold. The eagle figure perched on top of the standard with spread wings, holding Jupiter’s (the highest of the Roman gods) lightning bolts in its claws. Sometimes it also held an acorn in its beak, which also symbolized the supreme god Jupiter, whose holy tree was the oak.
The bearer of the legionary eagle, called »aquilifer,« usually was a sergeant of outstanding merit, who was superior to all other standard bearers of his legion. He ranked directly below the centurion in the legion’s hierarchy. Apparently, sergeants who were close to retirement were given the opportunity to do this honorable job.
The bearer of the standard (»signifer«) was particularly noticeable amongst the legionnaires. He wore the skin of a wolf, a bear or a lion over his armor. The head and the upper jaw of the animal, which had undergone taxidermy, were pulled over the signifer’s helmet while the fur hung over his back. The front paws were draped around his shoulders so that they could be tied together in the front. This outfit was often supplemented with a masked helmet, rendering the signifer completely unrecognizable. In this way he looked fearsome enough to be able to bear the religiously worshipped insignia as a symbol of the entire legion.
The insignia were not only of tactical relevance, but they were also a desired spoil of war. Therefore, the signifer’s job was quite challenging: Not only did he have to survive in battle while being handicapped by the standard, but in his high position he also served as an inspiring example for the soldiers of his legion. His only weapon to defend himself was a small, round cavalry shield called »parma equestris.«
Another task of the signifier was cash management for the legion, which meant that he had to be able to write and calculate well. Therefore, a signifer could rise to the rank of centurion, the influential leader of a century.