Titus Livius (Livy), The History of Rome, Book 28
Frank Gardener Moore, Professor Emeritus in Columbia University, Ed.

1. WHILE the passage of Hasdrubal,¹ by shifting² the war to Italy, was felt to have lightened in proportion the burden for Spain, suddenly a war as dangerous as the former broke out again in that country. [2] Spanish territory was at that time occupied by Romans and Carthaginians as follows: [3] Hasdrubal son of Gisgo had retired all the way to the Ocean and Gades; the coast of Our Sea and nearly all of Spain facing eastward were under Scipio and Roman rule; [4] a new commander, Hanno,³ as successor to Hasdrubal Barca had crossed over from Africa with a new army, and uniting with Mago, had promptly armed men in large numbers in Celtiberia, which lies directly between the two seas. [5] Whereupon Scipio sent Marcus Silanus⁴ with not more than ten thousand infantry and five hundred cavalry against Hanno. Silanus made his marches as long [p. 5]as possible, being hampered, however, both by rough⁵ roads and narrow passes frequently hemmed in by wooded mountains, as is usual in Spain. [6] Nevertheless he outstripped not only messengers reporting his approach but even rumours of it, and guided by deserters from the same Celtiberia he made his way to the enemy. [7] From the same informants it was learned, when they were about ten miles from the enemy, that there were two camps, one on each side of the road along which they were moving; that, on the left lay the Celtiberians, a new army, over nine thousand men, on the right the Carthaginian camp; [8] that this was strongly defended by outposts, sentries and all the protection usual in the field, while the other camp was lax and carelessly guarded, as belonging to barbarians who were raw recruits and less afraid because they were in their own country.

Silanus, thinking this camp must be attacked first, ordered the standards to move as far to the left as possible, for fear he might be seen from somewhere by the Carthaginian outposts. [9] He sent scouts in advance and himself proceeded towards the enemy with a swiftly moving column.