The battle of Motyum (451 BC) was the most important battlefield victory won by the Sicel leader Ducetius, but he was defeated at Nomae in the following year and forced into exile.
Ducetius first appeared in 461 BC when he cooperated with the Syracusans in an attack on Catana. Over the next few years he appears to have concentrated on consolidating his power over the Sicels and in 453/2 he established a new administrative and religious capital at Palice.
After creating a powerful Sicel league Ducetius decided to turn on the Greeks. His first target was the city of Aetna, founded by the defeated colonists of Catana. In 451 Ducetius captured this city. He then moved south and besieged Motyum, a city held and garrisoned by the city of Akragas (a major Greek city on the south coast of Sicily).
This was a direct threat to the Greek powers of Sicily. Akragas and Syracuse both raised armies and late in the autumn advanced towards Motyum to lift the siege.
Ducetius must have raised quite a powerful army by 451 BC, for when the combined Greek armies approached he was willing to offer battle. The resulting fight ended as a victory for Ducetius. Both Greek armies were forced to abandon their camps, and retreated back to their home cities.
In Syracuse a scapegoat was soon found. Bolcon, commander of the Syracusan army at the battle was accused of having secret dealing with Ducetius, convicted of treason and executed. Diodorus doesn't tell us what happened in Akragas.
Ducetius's triumph would be short-lived. In 450 BC both Syracuse and Akragas put fresh armies into the field. This time the Syracusans defeated Ducetius at the battle of Nomae, while Akragas recaptured Motyum. Ducetius sought protection in Syracuse, and was briefly exiled from Sicily.