Titus Livius (Livy), The History of Rome, Book 23
Frank Gardener Moore, Professor Emeritus in Columbia University, Ed.

27. After the Tartesii had repeatedly failed to draw the Carthaginian out to battle by facing his camp, and it was also not easy to assault the camp, they took by storm the city of Ascua, to which Hasdrubal, on entering the land of the enemy, had brought grain and other supplies; [2] and they gained possession of all the country around. [3] And they could no longer be restrained by any authority either on the march or in camp. Hasdrubal, perceiving that this carelessness came, as usually happens, from success, exhorted his soldiers to attack the enemy while dispersed and in no formation, and coming down from the hill he proceeded to their camp in battle order. [4] When his approach was reported by messengers fleeing wildly from the watch-towers and guard-posts, they shouted “To arms!” [5] Snatching up arms, each man for himself, without commanders, without orders, in no units or formations, they dashed into battle. Already the first men had engaged, while some charged in separate masses and others had not yet left the camp. [6] Nevertheless they at first frightened the enemy by sheer audacity. Then, as stragglers advancing against dense ranks, finding no safety in small numbers, they looked to one another for help; and, beaten back from every side, they formed a circle. [7] And as they crowded bodies against bodies and touched arms to arms, they were forced into close quarters. Having hardly room enough to move their weapons, they were encircled by the enemy, and the slaughter continued until late in the [p. 93]day. [8] A very small part of them sallied out and made¹ for the woods and the mountains. In no less alarm the camp was abandoned, and on the next day the whole tribe surrendered.

Yet not for long did the tribe abide by the agreement. [9] For soon came the order from Carthage that Hasdrubal should at the first opportunity lead his army into Italy. And the spreading of this news throughout Spain made nearly all incline to the side of the Romans.² [10] Accordingly Hasdrubal at once sent a letter to Carthage, showing what a loss the mere report of his departure had caused; that if he were actually to leave the country, Spain would belong to the Romans before he should cross the Hiberus.³ [11] For besides the lack of both an army and a general to leave in his place, so able were the Roman generals that they could scarcely be resisted if the forces were evenly matched. [12] And so, if they had any regard for Spain, they should send him a successor with a strong army. Even if all should go well, that man would still find it no peaceful province.