TACTICS OF THE ARMY.
§ 93. The core of the Roman army was the legion. Hence we see that in describing the battle array of the legion, we have very nearly explained the mode of battle of the army as a whole.
§ 94. It is clear that the normal order with the Romans was the offensive. Cæsar usually employed the triple line (acies triplex). The legions that composed the line of battle stood side by side, each in three lines.
The third line was designed as a reserve for the other two. The Roman method was to hurl the first line against the enemy. Should this onset not suffice, or should the first line become exhausted, then the second line in turn took up the attack, while the first retired between the intervals and rested. Thus the two lines alternately assailed the foe, until the latter should break. Meanwhile the third line was in reserve. Should the enemy attempt a flank movement, this line was deployed to the left or right to meet it. If no such movement was attempted, or if auxiliaries were at hand to meet it, the third line was held in reserve until the crisis of the battle. Then it was hurled at the enemy in a decisive charge.
Often, also, the third line was busied in fortification, while the first and second covered the work.
B. G. I, 25, 52. C. III, 89, 94.
§ 95. In case a reserve seemed unnecessary, or a greater extension of front was desirable, the legions were formed in