negyr. c. 13. Life of Hadrian, in the Augustan
History.]

Nine centuries of war had gradually introduced into the service many
alterations and improvements. The legions, as they are described by
Polybius, [41] in the time of the Punic wars, differed very materially
from those which achieved the victories of Caesar, or defended the
monarchy of Hadrian and the Antonines.

The constitution of the Imperial legion may be described in a few words.
[42] The heavy-armed infantry, which composed its principal strength, [43]
was divided into ten cohorts, and fifty-five companies, under the orders
of a correspondent number of tribunes and centurions. The first cohort,
which always claimed the post of honor and the custody of the eagle, was
formed of eleven hundred and five soldiers, the most approved for valor
and fidelity. The remaining nine cohorts consisted each of five hundred
and fifty-five; and the whole body of legionary infantry amounted to six
thousand one hundred men. Their arms were uniform, and admirably adapted
to the nature of their service: an open helmet, with a lofty crest;
a breastplate, or coat of mail; greaves on their legs, and an ample
buckler on their left arm. The buckler was of an oblong and concave
figure, four feet in length, and two and a half in breadth, framed of a
light wood, covered with a bull's hide, and strongly guarded with plates
of brass. Besides a lighter spear, the legionary soldier grasped in
his right hand the formidable pilum, a ponderous javelin, whose
utmost length was about six feet, and which was terminated by a massy
triangular point of steel of eighteen inches. [44] This instrument was
indeed much inferior to our modern fire-arms; since it was exhausted
by a single discharge, at the distance of only ten or twelve paces.
Yet when it was launched by a firm and skilful hand, there was not any
cavalry that durst venture within its reach, nor any shield or corselet
that could sustain the impetuosity of its weight. As soon as the Roman
had darted his pilum, he drew his sword, and rushed forwards to close
with the enemy. His sword was a short well-tempered Spanish blade, that
carried a double edge, and was alike suited to the purpose of striking
or of pushing; but the soldier was always instructed to prefer the
latter use of his weapon, as his own body remained less exposed, whilst
he inflicted a more dangerous wound on his adversary. [45] The legion was
usually drawn up eight deep; and t