That they ought to give the signal for battle instantly, and march out into the field, and take advantage of the delusion of their enemies present and absent, while neither those were aware that they had fewer, nor these that they had more and stronger forces to encounter." On the breaking up of the council the signal for battle was displayed, and the troops immediately led into the field.
47.

The Carthaginians were already standing before their camp in battle-array.

This circumstance delayed the battle: Hasdrubal, who had advanced before the line with a few horsemen, remarked some old shields among the enemy, which he had not seen before, and some horses leaner than the rest their numbers also appeared greater than usual.
Suspecting therefore, what was really the case, he hastily sounded a retreat, and sent a party to the river from which they got their water, where some of them might be intercepted, and notice taken whether there were perchance any there whose complexions were more than ordinarily sun-burnt, as from a recent march.

At the same time he ordered a party to ride round the camp at a distance, and note whether the rampart was extended in any part, and also observe whether the signal sounded once or twice.

Having received a report of all these particulars, the fact of the camp's not being enlarged led him into error.