Hasdrubal Barca, the Carthaginian commander in Iberia, had launched a joint expedition to destroy the Roman base north of the Ebro River.

The reputation of the Romans was further enhanced in Iberia after this victory, causing rebellion among some of the Iberian tribes under Carthaginian control.

Meanwhile, Hasdrubal Barca, the Carthaginian commander in Iberia, had raised a number of Iberian levies to expand his army substantially.

Gnaeus Scipio, fearing that the Carthaginian army outnumbered his own, resolved to fight a naval battle; though he could only man 35 quinqueremes[3] (25 ships were sent back to Italy after a Carthaginian raid in late 218 caused severe casualties among the crews, and some sailors may have been posted in garrisons) however, the Romans were supported by 20 ships from Massalia.

A pair of Massalian ships located the Punic fleet as it lay at anchor, and slipped away undetected to warn Gnaeus of the Carthaginian presence.

The combat effectiveness of the Carthaginians is not reflected in the number of ships as one-quarter of their fleet had newly trained crew.

With the Iberian contingent of the Carthaginian navy shattered, Hasdrubal was forced to either call Carthage for reinforcements or build new ships.

The performance of the Iberian crews had been poor in the battle, and their dismissal would spark a rebellion in the Turdetani tribe,[6] forcing Carthage to send 4,000 infantry and 500 cavalry to Hasdrubal.