[3] In Plutarch's account, after resting his army, Pyrrhus marched to Asculum to confront the Romans.

The 1st century AD Roman senator Frontinus estimated a strength of 40,000 men for both sides.

[5] Pyrrhus had men from Thesprotia, Ambracia, and Chaon, two cities and a district in Epirus, and mercenaries from the Aetolians, Acarnanians, and Athamanians.

Among the allies of Rome mentioned by Dionysius of Halicarnassus there were the Frentani, Marrucini, Paeligni, Dauni, and Umbrians.

Since Pyrrhus' elephants had caused much terror and destruction in the Battle of Heraclea, the Romans devised special wagons against them.

Many poles protruded in front of the wagons and had fire-bearing grapnels wrapped in cloth daubed with pitch.

[7] Pyrrhus lined up the Macedonian phalanx of the Epirots and Ambracians, mercenaries from Tarentum with white shields, and the Bruttii and Lucani allies on the right wing.

On the left wing were the Ambracian, Lucanian, and Tarentine squadrons and Acarnanian, Aetolian, Macedonian, and Athamanian mercenaries.

Pyrrhus divided the light infantry and the elephants into two groups and placed them behind the wings, on a slightly elevated position.

However, he was forced into an area where, due to the wooded banks of the river, he could not deploy the cavalry or use his elephants against the Romans.

During the night Pyrrhus sent a detachment to occupy the unfavourable areas of the field so that he could fight and deploy his elephants on level ground.

They fought fiercely with their swords against the Macedonian pikes, in an attempt to repulse the enemy troops before the elephants could charge.

There were rumours that Publius Decius Mus (one of the two consuls for 279 BC) was getting ready to devote himself like his father and grandfather.

Pyrrhus endeavoured to reassure them and ordered them to seize alive anyone who wore the garments the Decii family used when devoting themselves.

The Romans asked whether Pyrrhus would choose to cross it unmolested or whether he would allow them to do so unharmed so that the two forces would fight intact, thus giving an accurate test of their valour.

The Romans gradually forced the Epirotes back until Pyrrhus moved the elephants to the other end of the line, away from the wagons.

This won the battle for the Romans because when Pyrrhus sent some of his men against them, the rest suspected that the camp had fallen and that their companions had fled.

Lightly-armed Greek troops attacked the wagons and those who manned them fled into the nearest infantry line, throwing it into confusion.

The Bruttii and Lucanians in the middle of the formation of Pyrrhus fled when they were repulsed by the Roman fourth legion.

Some of the Daunians from Arpi (4000 infantry and 4000 cavalry), who had been sent to help, got close to Pyrrhus’ camp by chance while travelling on a road that led to the enemy's rear.

Pyrrhus, whose forces had lost the tents, pack-animals and baggage which were kept in the camp, encamped on a hill and spent the night outdoors and without food.

Plutarch also wrote that Pyrrhus said to someone who was congratulating him: "If we are victorious in one more battle with the Romans, we shall be utterly ruined."

The Romans, instead, could quickly replenish their forces "as if from a fountain gushing forth indoors", and did not lose courage or determination in defeat.

After this he wanted to build a large fleet to invade Carthage's home territory in Africa.