formed the first line in battle. The _principes_ were men of
middle age who occupied the second line. The _triarii_ were old soldiers
of approved valor, who formed the third line.

There was a fourth kind of troops, called _vel{)i}tes_ from their
swiftness and agility: these did not form a part of the legion, and had
no certain post assigned them, but fought in scattered parties, wherever
occasion required, usually before the lines.

The imperial eagle was the common standard of the legion; it was of gilt
metal, borne on a spear by an officer of rank, styled, from his office,
_aquilifer_, and was regarded by the soldiery with the greatest
reverence. There were other ensigns, as A. B. C. D. in the frontispiece.

The only musical instruments used in the Roman army, were brazen
trumpets of different forms, adapted to the various duties of the
service.

The arms of the soldiery varied according to the battalion in which they
served. Some were equipped with light javelins, and others with a
missile weapon, called _pilum_, which they flung at the enemy; but all
carried shields and short swords of that description, usually styled cut
and thrust, which they wore on the right side, to prevent its
interfering with the buckler, which they bore on the left arm.

The shield was of an oblong or oval shape, with an iron boss jutting out
in the middle, to glance off stones or darts; it was four feet long and
two and a half broad, made of pieces of wood joined together with small
plates of iron, and the whole covered with a bull's hide.

They were partly dressed in a metal cuirass with an under covering of
cloth; on the head they wore helmets of brass, either fastened under the
chin, with plates of the same metal, or reaching to the shoulders, which
they covered and ornamented on the top with flowing tufts of horse hair.

The light infantry were variously armed with slings and darts as well as
swords, and commonly wore a shaggy cap, in imitation of the head of some
wild beast, of which the skirt hung over their shoulders. The troops of
the line wore greaves on the legs and heavy iron-bound sandals on the
feet. These last were called _caligae_, from which the emperor Caius
Caesar obtained the name of Caligula, in consequence of having worn them
in his youth among the soldiery.

The cavalry were armed with spears and wore a coat of mail of chain
work, or scales of brass or steel, often plated with gold, under which
was a close ga