The Spanish general made no attempt to pursue, or even to molest his adversary in his retreat. For this he has been severely criticized, more particularly as the passage of a river offers many points of advantage to an assailant. But, in truth, Alva never resorted to fighting when he could gain his end without it. In an appeal to arms, however favorable may be the odds, there must always be some doubt as to the result. But the odds here were not so decisively on the side of the Spaniards as they appeared. The duke of Guise carried off his battalions in admirable order, protecting his rear with the flower of his infantry and with his cavalry, in which last he was much superior to his enemy. Thus the parts of the hostile armies likely to have been brought into immediate conflict would have afforded no certain assurance of success to the Spaniards. Alva's object had been, not so much to defeat the French as to defend Naples. This he had now achieved, with but little loss; and rather than incur the risk of greater, he was willing, in the words of an old proverb, to make a bridge of silver for the flying foe.[165] In the words of Alva himself, "he had no idea of staking the kingdom of Naples against the embroidered coat of the duke of Guise."[166] On the retreat of the French, Alva laid siege at once to two or three places, of no great note, in the capture of which he and his lieutenants were guilty of the most deliberate cruelty; though, in the judgment of the chronicler, it was not cruelty, but a wholesome severity, designed as a warning to such petty places not to defy the royal authority.[167] Soon after this, Alva himself crossed the Tronto, and took up a position not far removed from the French, who lay in the neighborhood of Ascoli. Although the two armies were but a few miles asunder, there was no attempt at hostilities, with the exception of a skirmish in which but a small number on either side were engaged, and which terminated in favor of the Spaniards. This state of things was at length ended by a summons from the pope to the French commander to draw nearer to Rome, as he needed his presence for the protection of the capital. The duke, glad, no doubt, of so honorable an apology for his retreat, and satisfied with having so long held his ground against a force superior to his own, fell back, in good order, upon Tivoli, which, as it commanded the great avenues to Rome on the east, and afforded good accommodations for his troops, he made his head quarters for the present. The manner in which the duke of Alva adhered to the plan of defensive operations settled at the beginning of the campaign, and that, too, under circumstances which would have tempted most men to depart from such a plan, is a remarkable proof of his perseverance and inflexible spirit. It proves, moreover, the empire which he held over the minds of his followers, that, under such circumstances, he could maintain implicit obedience to his orders.