The camp of a Roman legion presented the appearance of a fortified city. As soon as the space was marked out, the pioneers carefully levelled the ground, and removed every impediment that might interrupt its perfect regularity. Its form was an exact quadrangle; and we may calculate, that a square of about seven hundred yards was sufficient for the encampment of twenty thousand Romans; though a similar number of our own troops would expose to the enemy a front of more than treble that extent. In the midst of the camp, the prætorium, or general’s quarters, rose above the others; the cavalry, the infantry, and the auxiliaries occupied their respective stations; the streets were broad and perfectly straight, and a vacant space of two hundred feet was left on all sides between the tents and the rampart. The rampart itself was usually twelve feet high, armed with a line of strong and intricate palisades, and defended by a ditch of twelve feet in depth as well as in breadth. This important labor was performed by the hands of the legionaries themselves; to whom the use of the spade and the pickaxe was no less familiar than that of the sword or _pilum_. Active valor may often be the present of nature; but such patient diligence can be the fruit only of habit and discipline. Whenever the trumpet gave the signal of departure, the camp was almost instantly broke up, and the troops fell into their ranks without delay or confusion. Besides their arms, which the legionaries scarcely considered as an encumbrance, they were laden with their kitchen furniture, the instruments of fortification, and the provision of many days. Under this weight, which would oppress the delicacy of a modern soldier, they were trained by a regular step to advance, in about six hours, near twenty miles. On the appearance of an enemy, they threw aside their baggage, and by easy and rapid evolutions converted the column of march into an order of battle. The slingers and archers skirmished in the front; the auxiliaries formed the first line, and were seconded or sustained by the strength of the legions; the cavalry covered the flanks, and the military engines were placed in the rear.