A battle was usually commenced by the light troops, who skirmished with missile weapons; the hasta'ti then advanced to the charge, and if defeated, fell back on the prin'cipes; if the enemy proved still superior, the two front lines retired to the ranks of the tria'rii, which being composed of veteran troops, generally turned the scale.
But this order was not always observed; the number of divisions in the legion made it extremely flexible, and the commander-in-chief could always adapt the form of his line to circumstances.
11.

The levies of troops were made in the Cam'pus Mar'tius, by the tribunes appointed to command the legions.

The tribes which were to supply soldiers were determined by lot, and as each came forward, the tribunes, in their turn, selected such as seemed best fitted for war.
Four legions was most commonly the number in an army.

When the selected individuals had been enrolled as soldiers, one was chosen from each legion to take the military oath of obedience to the generals; the other soldiers swore in succession, to observe the oath taken by their foreman.
12.

Such was the sacredness of this obligation, that even in the midst of the political contests by which the city was distracted, the soldiers, though eager to secure the freedom of their country, would not attempt to gain it by mutiny against their commanders.