But at sunrise that same morning the signal had been given for the passage of the elephants, and the Carthaginians had started on their way to the Alps, the heavy-armed infantry in front, with the cavalry in the rear to protect them. Hannibal himself was determined not to stir till the elephants were safely over, but everything fell out as he expected, and the whole thirty-seven were soon safe beside him on dry land, snorting and puffing with their trunks in the air. Then he followed his main body, and when Scipio, thirsting to give battle to the enemy he felt sure of conquering, arrived at the spot where three days before the Carthaginian army had been encamped, he found it empty. [Illustration: Hannibal was determined not to stir until the elephants were safely over.] Nothing is so necessary to the success of a campaign as having correct maps and information about the country through which your army has to pass. Hannibal, who thought of everything, had thought of this also, and had paid native guides well to lead him to the nearest passes over the Alps. For four days the Carthaginians marched along the Rhone, till they reached the place where the river Isere flows into it. The Gallic chief of the tribes settled in this part of Gaul, being at war with his brother, was easily gained over by some assistance of Hannibal's in securing his rights, and in return he furnished the Carthaginians with stores from the rich lands he ruled, with new clothes and strong leather sandals, and, more precious than all, with fresh weapons, for their own had grown blunted and battered in many a grim fight since the soldiers left Carthagena. At the foot of the pass leading over the Mont du Chat, or Cat Mountain, in a lower range of the Alps, the chief bade them farewell, and returned to his own dominions. It was then that Hannibal's real difficulties began. His army consisted of many races, all different from each other, with different customs and modes of warfare, worshippers of different gods. There were Iberians from Spain, Libyans and Numidians from Africa, Gauls from the south of France; but they one and all loved their general, and trusted him completely, and followed blindly where he led. Still, the plunge into those silent heights was a sore trial of their faith, and in spite of themselves they trembled. As they began their climb they found the pass occupied by numbers of Gallic tribes ready to hurl down rocks on their heads, or attack them at unexpected places. Perceiving this, Hannibal called a halt, while his native scouts stole away to discover the hiding-places of the enemy, and, as far as possible, how they intended to make their assault.