While, deceived by these appearances, Indutiomarus became daily more presumptuous, Labienus introduced secretly into his camp during the night the auxiliary cavalry, and, by keeping a close watch, prevented the Treviri from being informed of it. The enemy, ignorant of the arrival of this re-enforcement, advanced nearer and nearer to the retrenchments, and redoubled his provocations. They were unnoticed, and towards evening he withdrew in disorder. Suddenly Labienus causes his cavalry, seconded by his cohorts, to issue by the two gates. Foreseeing the rout of the enemy, he urges his troops to follow Indutiomarus alone, and promises great rewards to those who shall bring his head. Fortune seconded his designs; Indutiomarus was overtaken just at the ford of the river (the Ourthe), and put to death, and his head was brought into the camp. The cavalry, in their return, slew all the enemies they found in their way. The Eburones and the Nervii dispersed. The result of these events was to give to Gaul a little more tranquillity.[446] [Sidenote: Observations.] XVI. The Emperor Napoleon, in his _Précis des Guerres de César_, explains in the following manner the advantage the Romans drew from their camps:-- “The Romans owe the constancy of their successes to the method, from which they never departed, of encamping every night in a fortified camp, and of never giving battle without having behind them a retrenched camp, to serve them as a place of retreat, and to contain their magazines, their baggage, and their wounded. The nature of arms in those ages was such that, in these camps, they were not only in safety from the attacks of an equal army, but even an army which was stronger; they were the masters to fight or to wait a favourable opportunity. Marius is assailed by a cloud of Cimbri or Teutones; he shuts himself up in his camp, remains there until the favourable day or occasion comes, then he issues with victory before him. Cæsar arrives near the camp of Cicero; the Gauls abandon the latter, and march to meet the former; they are four times more numerous. Cæsar takes a position in a few hours, retrenches his camp, and in it he bears patiently the insults and provocations of an enemy whom he is not yet willing to combat; but a favourable opportunity is not long in presenting itself. He then issues through all his gates; the Gauls are vanquished. “Why, then, has a rule so wise, so fertile in great results, been abandoned by modern generals? Because offensive arms have changed its character; arms for the hand were the principal arms of the ancients; it was with his short sword that the legionary conquered the world; it was with the Macedonian pike that Alexander conquered Asia. The principal arms of modern armies are projectiles; the musket is superior to anything ever invented by man; no defensive arm is a protection against it.