Niccolò Machiavelli
Discourses on the First Decade of Titus Livius (Chap. 1.15) (English version)
How the Samnites, as a last resource in their broken Fortunes, had recourse to Religion.

The Samnites, who before had met with many defeats at the hands of the Romans, were at last decisively routed by them in Etruria, where their armies were cut to pieces and their commanders slain. And because their allies also, such as the Etruscans, the Umbrians, and the Gauls, were likewise vanquished, they "could now no longer" as Livius tells us, "either trust to their own strength or to foreign aid; yet, for all that, would not cease from hostilities, nor resign themselves to forfeit the liberty which they had unsuccessfully defended, preferring new defeats to an inglorious submission._" They resolved, therefore, to make a final effort; and as they knew that victory was only to be secured by inspiring their soldiers with a stubborn courage, to which end nothing could help so much as religion, at the instance of their high priest, Ovius Paccius, they revived an ancient sacrificial rite performed by them in the manner following. After offering solemn sacrifice they caused all the captains of their armies, standing between the slain victims and the smoking altars, to swear never to abandon the war. They then summoned the common soldiers, one by one, and before the same altars, and surrounded by a ring of many centurions with drawn swords, first bound them by oath never to reveal what they might see or hear; and then, after imprecating the Divine wrath, and reciting the most terrible incantations, made them vow and swear to the gods, as they would not have a curse light on their race and offspring, to follow wherever their captains led, never to turn back from battle, and to put any they saw turn back to death. Some who in their terror declined to swear, were forthwith slain by the centurions. The rest, warned by their cruel fate, complied. Assembling thereafter to the number of forty thousand, one-half of whom, to render their appearance of unusual splendour were clad in white, with plumes and crests over their helmets, they took up their ground in the neighbourhood of Aquilonia. But Papirius, being sent against them, bade his soldiers be of good cheer, telling them "that feathers made no wounds, and that a Roman spear would pierce a painted shield;" and to lessen the effect which the oath taken by the Samnites had upon the minds of the Romans, he said that such an oath must rather distract than strengthen those bound by it, since they had to fear, at once, their enemies, their comrades, and their Gods. In the battle which ensued, the Samnites were routed, any firmness lent them by religion or by the oath they had sworn, being balanced by the Roman valour, and the terror inspired by past defeats. Still we see that, in their own judgment, they had no other refuge to which to turn, nor other remedy for restoring their broken hopes; and this is strong testimony to the spirit which religion rightly used can arouse.

Some of the incidents which I have now been considering may be thought to relate rather to the foreign than to the domestic affairs of Rome, which last alone form the proper subject of this Book; nevertheless since the matter connects itself with one of the most important institutions of the Roman republic, I have thought it convenient to notice it here, so as not to divide the subject and be obliged to return to it hereafter.