So passed the winter.  Early in the spring a messenger arrived from Hannibal bidding Malchus rejoin him, and calling upon Allobrigius to prepare to take the field against the Romans.  Similar messages had been sent to all the Gaulish tribes friendly to Carthage, and early in March Hannibal prepared to cross the Apennines and to advance against Rome.

The position occupied by the two Roman armies barred the only two roads by which it was believed that Hannibal could march upon Rome, but as soon as the spring commenced Hannibal started by a path, hitherto untrodden by troops, across the Apennines.  In the march the troops suffered even greater hardships than those which they had undergone in the passage of the Alps, for during four days and three nights they marched knee deep in water, unable for a single moment to lie down.

While ever moving backwards and forwards among his men to encourage them with his presence and words, even the iron frame of Hannibal gave way under the terrible hardships.  The long continued strain, the want of sleep, and the obnoxious miasma from the marshes, brought on a fever and cost him the sight of one of his eyes.  Of all the elephants but one survived the march, and it was with an army as worn out and exhausted as that which had issued from the Alps that he descended into the fertile plains of Tuscany, near Fiesole.

The army of Flaminius, 30,000 strong, was still lying at Arezzo, on his direct road south, and it was with this only that Hannibal had now to deal, the force of Servilius being still far away at Rimini.  His own army was some 35,000 strong, and crossing the Upper Arno near Florence, Hannibal marched towards Arezzo.  Flaminius, as soon as he had heard that Hannibal was ascending the slopes of the Apennines, had sent to Servilius to join him, but the latter, alleging that he feared an invasion by the Gaulish tribes on the north, refused to move, but sent four thousand cavalry to Flaminius.  This brought the armies to nearly equal strength, but, although Hannibal marched his troops within sight of Arezzo, Flaminius would not issue from his camp to attack him.

He knew that Hannibal had defeated a force of tried troops, much exceeding his own in numbers, in the north, and that he would therefore probably be successful against one which scarcely equalled his own.  He hoped, too, that Hannibal would attack him in his intrenched position.  This the Carthaginian general had no intention of doing, but, leaving the camp behind him, marched on, plundering and ravaging the country towards Rome.  Flaminius at once broke up his camp and followed on his track, preparing to take any opportunity which might occur to fall upon the Carthaginians, and knowing that the senate would at once call up the army of Servilius to assist him.

Hannibal, by means of scouts left in his rear, found that Flaminius was marching on with his troops in solid column, taking no precaution against surprise, secure in the belief that Hannibal’s object was to march on Rome without a stop.  The Carthaginian general prepared at once to take advantage of his enemy’s carelessness.  He halted his troops at Cortona.  The road by which he had passed wound along the shore of Lake Trasimene, at the foot of a range of steep hills, which approached closely to the water.