+79.+ But after a careful inquiry as to what part of the road was firm or boggy, Hannibal broke up his camp and marched out. He placed the Libyans and Iberians and all his best soldiers in the van, and the baggage within their lines, that there might be plenty of provisions for their immediate needs. Provisions for the future he entirely neglected. Because he calculated that on reaching the enemy’s territory, if he were beaten he should not require them, and if he were victorious he would find abundance in the open country. Behind this vanguard he placed the Celts, and in the rear of all the cavalry. He entrusted the command of the rear-guard to his brother Mago, that he might see to the security of all, and especially to guard against the cowardice and impatience of hard labour which characterised the Celts; in order that, if the difficulty of the route should induce them to turn back, he might intercept them by means of the cavalry and force them to proceed. In point of fact, the Iberians and Libyans, having great powers of endurance and being habituated to such fatigues, and also because when they marched through them the marshes[186] were fresh and untrodden, accomplished their march with a moderate amount of distress: but the Celts advanced with great difficulty, because the marshes were now disturbed and trodden into a deep morass: and being quite unaccustomed to such painful labours, they bore the fatigue with anger and impatience; but were hindered from turning back by the cavalry in their rear. All however suffered grievously, especially from the impossibility of getting sleep on a continuous march of four days and three nights through a route which was under water: but none suffered so much, or lost so many men, as the Celts. Most of his beasts of burden also slipping in the mud fell and perished, and could then only do the men one service: they sat upon their dead bodies, and piling up baggage upon them so as to stand out above the water, they managed to get a snatch of sleep[187] for a short portion of the night. Another misfortune was that a considerable number of the horses lost their hoofs by the prolonged march through bog. Hannibal himself was with difficulty and much suffering got across riding on the only elephant left alive, enduring great agony from a severe attack of ophthalmia, by which he eventually lost the sight of one eye, because the time and the difficulties of the situation did not admit of his waiting or applying any treatment to it. [Sidenote: Hannibal in the valley of the Arno.]