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

16. Scipio, when men on outpost duty reported at daylight that the enemy had left, sent his cavalry ahead and ordered the standards to advance. [2] The column also marched at such a pace that, if they had directly followed the enemy's track, they would undoubtedly have overtaken them. They believed the guides that there was another shorter road to the river Baetis, by which they might attack the enemy while crossing over. [3] Hasdrubal, finding the passage [p. 69]of the river closed, turned aside towards the Ocean,^{1 2} and henceforward, scattering like fugitives, away they went. Thus he put a considerable distance between himself and the Roman [4] legions. Cavalry and light-armed, dashing upon them now from the rear, now on the flanks, kept wearing them out and delaying [5] them. But when in view of the numerous clashes the standards came to a halt and the men were engaged now with cavalry, now with skirmishers and auxiliary infantry, the legions came [6] up. Thereafter it was no longer a battle but a slaughter as of cattle, until the general, himself now approving their flight, escaped to the nearest hills with some six thousand half-armed men. The rest were slain or [7] captured. The Carthaginians hastily fortified an improvised camp on a very high hill and from it they defended themselves without difficulty, since the enemy had tried in vain to come up the steep [8] slope. But in an exposed situation which furnished nothing a siege was scarcely endurable even for a few days. Accordingly there were repeated desertions to the enemy. Finally the general himself sent for ships³ — the sea was not far away —and leaving his army by night he escaped to [9] Gades. Scipio, learning of the flight of the enemy's general, left Silanus ten thousand infantry and a thousand cavalry to besiege the [10] camp. With the rest of the forces he himself returned to Tarraco in seventy days' marches,⁴ hearing the cases of chiefs and states as he proceeded, in order to bestow rewards according to the real worth of their [11] services. After his departure [p. 71]Masinissa conferred secretly with Silanus, then crossed⁵ over to Africa with a few of his countrymen, in order that in changing his policy he might count upon the obedience of his nation [12] also. The reason for his sudden change was not so clear then as was later the evidence furnished by a loyalty unswerving down to extreme age,⁶ that even at that time he had not acted without a reasonable [13] ground. Mago then reached Gades on the ships sent back by Hasdrubal. The rest, abandoned by their generals, were scattered, some by desertion, others by flight, among the neighbouring states; no force remained which was notable for its numbers or its strength.

[14] So much in general for the manner in which under the command and auspices of Publius Scipio the Carthaginians were driven out of Spain in the fourteenth year⁷ from the beginning of the war, the fifth⁸ after Publius Scipio received his province and [15] army. Not much later Silanus returned to Scipio at Tarraco, reporting the war at an end.⁹