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

30. About the same time along the Baetis River Hanno, Mago's prefect, who-had been sent from Gades with a small force of Africans, enlisting Spaniards for pay, armed about four thousand young men. [2] Then stripped of his camp by Lucius Marcius, while the largest part of his troops were lost in the confusion of its capture, some also lost in the flight, since the cavalry pursued the scattered fugitives, Hanno himself with a small number only escaped.

[3] While these things were going on along the Baetis River, Laelius meantime sailed down the strait into the Ocean and came with his fleet to Carteia.¹ This city is situated on the coast of the Ocean, where [p. 125]the sea begins to open out after the narrow entrance.² [4] Of Gades, as has been said above, he had hoped without a battle to gain possession by betrayal,³ since men actually came into the Roman camp to make such a promise. But the betrayal was prematurely revealed, and Mago arrested all the conspirators and turned them over to Adherbal, the magistrate,⁴ to be transported to Carthage. [5] Adherbal placed the conspirators on a quinquereme and after sending it in advance, because it was slower than a trireme, himself followed with eight triremes at no great distance. [6] The quinquereme was already entering the strait when Laelius, also on a quinquereme, sailed out from the harbour of Carteia followed by seven triremes, and steered for Adherbal and his triremes, feeling quite sure that the quinquereme, caught in the swift current of the strait, could not reverse its course in the face of the tide. The Carthaginian in the unexpected situation was troubled for the moment and uncertain whether to follow his quinquereme or to turn his prows towards the enemy. [7] That hesitation in itself deprived him of the power to refuse a battle; for they were already within range and the enemy was pressing them from all sides. [8] The tide also had deprived them of control of their ships. Nor was the fight like a naval battle; for here there was no initiative, no skill or strategy. [9] The nature of the strait and its tide alone controlled the entire engagement, carrying men, vainly struggling to row in the opposite direction, against their own ships or those of the enemy. And one might have seen a fleeing ship swung about by a swirl [p. 127]and borne against the victors, and a pursuing ship,⁵ if it chanced upon an opposite current, turning away as if in flight. [10] In actual combat now one ship, aiming to ram a ship of the enemy with its beak, turning aslant would itself receive the blow of the other's beak. Another ship, exposing its beam to the enemy, would suddenly be swung and turned bow foremost. [11] While- between the triremes an indecisive battle controlled by chance was in progress, the Roman quinquereme, whether because she was steadier by reason of her weight or more easily steered as her more numerous banks of oars⁶ cleft the whirling waters, sank two triremes and shooting past another swept away the oars on one side. [12] In addition she would have seriously damaged the rest of the ships with which she had closed, had not: Adherbal with five remaining ships crossed over to Africa under sail.