The battle of Astura was one of two Roman victories during 338 BC that ended the Latin War of 340-338 BC. An allied army made up of elements from the Volscians of Antium and the Latin cities of Valitrae, Lanuvium and Aricia, were forming up on the River Astura, just to the east of Antium.
The local of the battle is something of a puzzle. According to Livy the Latin states had decided that they weren't strong enough to face the Romans in the field in 338, and so had decided to concentrate on defending their cities. If the Romans attacked any city then the other Latin states would send help. The main Roman effort of 338 was to be made against Pedum, due east of Rome. Valitrae, Lanuvium and Aricia, the three Latin cities whose armies were defeated at Astura, were located quite close together to the south-east of Rome, and yet they were defeated on the River Astura, twenty miles further south and just to the east of Antium. The question is why did those cities move their armies away from Pedum, and not towards it?
There are a number of possibilities. The first is that their Volscian allies at Antium insisted that the muster took place in their territory. Second, although Livy states that the main Roman effort was to be made against Pedum, only one of the two consuls is said to have taken part in the fighting around the city, so it is possible that Gaius Maenius was sent south to attack a different city, and the muster on the Astura was intended to deal with that threat. It is also possible that the Romans had advanced south-east towards the Latin cities, and the Latins had decided to retreat towards Antium to join up with their allies. Alternately the Roman presence around Pedum might have been strong enough to prevent the three Latin armies from moving north. Finally, the muster on the Astura might have been an offensive move, and the army intended for operations somewhere else in Roman territory.
Regardless of which (if any) of these possibilities is closest to the truth, the result was a disastrous defeat. Gaius Maenius, with his consular army, moved south, surprised and routed the allies on the Astura. Antium, for many years a thorn in Roman sides, was captured. Its powerful fleet was confiscated, and the bronze rams from the warships taken back to Rome, where they became the speaker's platform in the forum. A new group of Roman colonists were sent to the city, although the existing population was also allowed to enrol as citizens.
L. Furius Camillus had also been successful, defeating the Latin army that had gathered at Pedum and capturing the city. Both consuls were awarded triumphs, and a new settlement was agreed for Latium, which saw Roman citizenship extended into many new areas.