Titus Livius (Livy), The History of Rome, Book 27
Frank Gardner Moore, Professor Emeritus in Columbia University, Ed.

47. Already the enemy were standing in line before the camp. Delay in beginning the battle was due to Hasdrubal, in that, riding out in front of the standards with a few horsemen, he observed among the enemy old shields which he had not seen before and very lean horses; and he thought the numbers also larger than was usual. [2] For, suspecting what had happened, he promptly sounded the recall and sent men to the river from which the Romans were drawing water, that some Romans might be captured there and scanned to see whether any chanced to be more sunburned, as though from a recent march. [3] At the same time he ordered men to ride round the camps at a distance, and to notice whether the earthworks had been somewhere enlarged, and to mark whether the trumpet sounded once in the camp or twice.¹ [4] All this having been duly reported, the fact that the camps had not been enlarged deceived him. There were two of them, as there had been before the coming of the second consul, one that of Marcus Livius, the other that of Lucius Porcius. In neither case had anything been added to the fortifications to give ampler space for the tents. [5] The one thing that impressed an experienced general and one accustomed to a Roman enemy was their report that the trumpet had sounded once in the praetor's camp, twice in the consul's. There surely were two consuls, he thought, and sadly concerned he was how the one had got away from Hannibal. [6] Least of all could he suspect the fact-that Hannibal had been baffled and baulked to such an extent that he did not know where was the [p. 397]general, where was the army with which his camp² was formerly in contact. [7] Surely he had been deterred by no common disaster, and had not dared to pursue. Hasdrubal greatly feared that after all was lost he had himself come too late to assist, and that the Romans would have the same good fortune in Italy as in Spain. [8] At times he believed his own letter had not reached Hannibal, and that the consul, upon intercepting it, had made haste, in order to overpower him. Troubled by these anxieties, he had the fires put out and orders given at the first watch that they should pack up their baggage in silence, and then he commanded the standards to advance. [9] In the excitement and confusion of the night the guides were not closely watched, and one of them settled himself in a hiding-place he had previously determined upon, while the other swam across the river Metaurus, using a shallow place known to him. So the column, deserted by its guides, wandered at first about the country, and a considerable number, overcome by drowsiness and lack of sleep, threw themselves down anywhere and left few men with the standards. [10] Hasdrubal ordered the standard-bearers to move along the bank of the river,³ until daylight should disclose a road. And having made little progress, while describing blind circles along the bends and curves of the twisting stream he halted, intending to cross the river as [p. 399]soon as daylight should show a favourable crossing.⁴ [11] But inasmuch as the farther he marched away from the sea the higher were the banks that confined the stream, and hence he could not find a ford, by wasting the day he gave the enemy time to overtake him.