With it a treaty had been made by which the Tarentines agreed to certain limits beyond which their fleet was not to pass, and the Romans bound themselves not to allow their vessels to appear in the Gulf of Tarentum beyond the Lacinian promontory.

As usual, the Romans found no difficulty in evading their treaty whenever it should profit them.
Thurii was attacked by the Lucanians, and, despairing of aid from Tarentum, called on Rome for assistance.

As soon as domestic affairs permitted, war was declared against the Lucanians, and the wedge was entered which was to separate Magna Graecia from Hellas, and deliver the former over to Rome.
Pretending that the war was instigated by Tarentum, Rome decided to ignore the treaty, and sent a fleet of ten vessels into the Bay of Tarentum.

It was a gala day, and the people were assembled in the theatre that overlooked the bay when the ships appeared.

It was determined to punish the intrusion.