John C. Yardley and Dexter Hoyos (eds), Oxford World's Classics: Livy: Hannibal's War: Books Twenty-One to Thirty
While the consul was busy at Rome with ceremonies of propitiation and with the mobilization of troops, Hannibal had left his winter quarters. Word had come to him that the consul Flaminius had reached Arretium and so, although he was shown an easier but longer route, he took the shorter path through the marshes of the River Arno, which at that time was unusually high.
Hannibal directed the Spaniards and Africans—the very best of his veteran troops—to lead the line of march, taking their baggage within their ranks so they would not lack vital supplies if compelled to halt at any stage. He ordered the Gauls to follow them, and form the centre of the column, while the cavalry were to be in the last position. Finally, Mago and the light-armed Numidians were to bring up the rear. Mago had the special charge of keeping the Gauls in check, preventing them from slipping away, or stopping, if they tired of the long and gruelling journey (Gauls as a race having little tolerance for hardships of that kind).
The troops in front simply followed the lead of the guides, and they managed to keep up through the deep and almost bottomless morasses left by the river, despite being almost swallowed up by the mud and submerged in water. But the Gauls were unable to remain on their feet once they stumbled, or to extricate themselves from the deep holes; their spirit could not sustain their strength, nor hope their spirit. Some, physically exhausted, had difficulty dragging themselves along, and others, their spirit broken from fatigue, simply collapsed, and perished amongst the beasts of burden that themselves lay dying all around. Most debilitating of all was the sleeplessness they endured for four days and three nights. Everything was covered with water, and finding a dry spot to set down their wearied limbs was impossible. And so they would pile their baggage packs together in the water and lie down on them; or the cadavers of pack animals that were strewn in heaps all along their path provided as much of a bed as they needed. All they sought was something above water that would give them a moment's sleep.
As for Hannibal himself, he had been suffering from an eye-infection since the inclement spring weather with its alternating pg 69hot and cold temperatures, and now he rode the one surviving elephant to keep himself higher above the water. However, the sleep-deprivation, the damp nights, and the swampy atmosphere all had a bad effect on his head, and since there was no place and no time for treatment he went blind in one eye.*