A prudent Captain will do what he can to make it necessary for his own Soldiers to fight, and to relieve his Enemy from that necessity.
Elsewhere I have noted how greatly men are governed in what they do by Necessity, and how much of their renown is due to her guidance, so that it has even been said by some philosophers, that the hands and tongues of men, the two noblest instruments of their fame, would never have worked to perfection, nor have brought their labours to that pitch of excellence we see them to have reached, had they not been impelled by this cause. The captains of antiquity, therefore, knowing the virtues of this necessity, and seeing the steadfast courage which it gave their soldiers in battle, spared no effort to bring their armies under its influence, while using all their address to loosen its hold upon their enemies. For which reason, they would often leave open to an adversary some way which they might have closed, and close against their own men some way they might have left open.
Whosoever, therefore, would have a city defend itself stubbornly, or an army fight resolutely in the field, must before all things endeavour to impress the minds of those whom he commands with the belief that no other course is open to them. In like manner a prudent captain who undertakes the attack of a city, will measure the ease or difficulty of his enterprise, by knowing and considering the nature of the necessity which compels the inhabitants to defend it; and where he finds that necessity to be strong, he may infer that his task will be difficult, but if otherwise, that it will be easy.
And hence it happens that cities are harder to be recovered after a revolt than to be taken for the first time. Because on a first attack, having no occasion to fear punishment, since they have given no ground of offence, they readily surrender; but when they have revolted, they know that they have given ground of offence, and, fearing punishment, are not so easily brought under. A like stubbornness grows from the natural hostility with which princes or republics who are neighbours regard one another; which again is caused by the desire to dominate over those who live near, or from jealousy of their power. This is more particularly the case with republics, as in Tuscany for example; for contention and rivalry have always made, and always will make it extremely hard for one republic to bring another into subjection. And for this reason any one who considers attentively who are the neighbours of Florence, and who of Venice, will not marvel so much as some have done, that Florence should have spent more than Venice on her wars and gained less; since this results entirely from the Venetians finding their neighbouring towns less obstinate in their resistance than the Florentines theirs. For all the towns in the neighbourhood of Venice have been used to live under princes and not in freedom; and those who are used to servitude commonly think little of changing masters, nay are often eager for the change. In this way Venice, though she has had more powerful neighbours than Florence, has been able, from finding their towns less stubborn, to subdue them more easily than the latter, surrounded exclusively by free cities, has had it in her power to do.
But, to return to the matter in hand, the captain who attacks a town should use what care he can, not to drive the defenders to extremities, lest he render them stubborn; but when they fear punishment should promise them pardon, and when they fear for their freedom should a**ure them that he has no designs against the common welfare, but only against a few ambitious men in their city; for such a**urances have often smoothed the way to the surrender of towns. And although pretexts of this sort are easily seen through, especially by the wise, the ma** of the people are often beguiled by them, because desiring present tranquillity, they shut their eyes to the snares hidden behind these specious promises. By means such as these, therefore, cities innumerable have been brought into subjection, as recently was the case with Florence. The ruin of Cra**us and his army was similarly caused: for although he himself saw through the empty promises of the Parthians, as meant only to blind the Roman soldiers to the necessity of defending themselves, yet he could not keep his men steadfast, they, as we clearly gather in reading the life of this captain, being deceived by the offers of peace held out to them by their enemies.
On the other hand, when the Samnites, who, at the instance of a few ambitious men, and in violation of the terms of the truce made with them, had overrun and pillaged lands belonging to the allies of Rome, afterwards sent envoys to Rome to implore peace, offering to restore whatever they had taken, and to surrender the authors of these injuries and outrages as prisoners, and these offers were rejected by the Romans, and the envoys returned to Samnium bringing with them no hope of an adjustment, Claudius Pontius, who then commanded the army of the Samnites, showed them in a remarkable speech, that the Romans desired war at all hazards, and declared that, although for the sake of his country he wished for peace, necessity constrained him to prepare for war; telling them "that was a just war which could not be escaped, and those arms sacred in which lay their only hopes." And building on this necessity, he raised in the minds of his soldiers a confident expectation of success. That I may not have to revert to this matter again, it will be convenient to notice here those examples from Roman history which most merit attention. When Caius Manilius was in command of the legions encamped against Veii, a division of the Veientine army having got within the Roman intrenchments, Manilius ran forward with a company of his men to defend them, and, to prevent the escape of the Veientines, guarded all the approaches to the camp. The Veientines finding themselves thus shut in, began to fight with such fury that they slew Manilius, and would have destroyed all the rest of the Roman army, had not the prudence of one of the tribunes opened a way for the Veientines to retreat. Here we see that so long as necessity compelled, the Veientines fought most fiercely, but on finding a path opened for escape, preferred flight to combat. On another occasion when the Volscians and Equians pa**ed with their armies across the Roman frontier, the consuls were sent out to oppose them, and an engagement ensued. It so happened that when the combat was at its height, the army of the Volscians, commanded by Vectius Mescius, suddenly found themselves shut in between their own camp, which a division of the Romans had occupied, and the body of the Roman army; when seeing that they must either perish or cut a way for themselves with their swords, Vectius said to them, "Come on, my men, here is no wall or rampart to be scaled: we fight man with man; in valour we are their equals, and necessity, that last and mightiest weapon, gives us the advantage." Here, then, necessity is spoken of by Titus Livius as the last and mightiest weapon.
Camillus, the wisest and most prudent of all the Roman commanders, when he had got within the town of Veii with his army, to make its surrender easier and not to drive its inhabitants to desperation, called out to his men, so that the Veientines might hear, to spare all whom they found unarmed. Whereupon the defenders throwing away their weapons, the town was taken almost without bloodshed. And this device was afterwards followed by many other captains.