The First Punic War was started in 264 BC by the crisis in the city of Messana, a strategically important location on the straits separating Sicily from Italy.

At this stage in history things might have rested for some while in Italy, if it had not been for the legacy of Agathocles of Syracuse. During his reign Agathocles had made large use of free companies of highland mercenaries from the mainland. And the town of Messana (Messina) had fallen at Agathocles' death in 288 BC into the hands of one of these free companies - the Mamertines (Mamertini 'sons of Mars', after the Sabellian war-god Mamers) from Campania- who made themselves a nuisance to their neighbours on both coasts, and to all who used the Strait of Messina: Greek and Carthaginian alike.

The Mamertines had recently been in league with a company of their Campanian countrymen, who, being in the Roman service, had mutinied, seized Rhegium (across the Straits of Messina), and held it against the Romans for ten years. The revolt had been suppressed in 270 BC by Rome and dealt with them severely. The Romans had been aided by the commander of the Syracusan forces, Hieron (or Hiero as the Romans called him - he had been elected strategos of Syracuse in 275). In 265 Hiero won great pitched battle near Longanus River and was elected 'Tyrant' of Syracuse (as Hiero II 270-216 BC). The Mamertine takeover of Messana offered an excuse for intervention (just as the Romans had themselves intervened in Rhegium). Successful intervention by Hiero would be a significant strategic gain because Messana controlled part of NE Sicily, and the straits (the shortest crossing point between Sicily and Italy).

Hiero
In 265 BC Hiero thought it time to make an end of the Mamertine pirates. And so far as their own merits went, no one was likely to be aggrieved. But if he did, what was to happen to Messana and who had something to gain by using the Mamertines to obtain a footing there, or to prevent Hiero from gaining one Hiero besieged the city captured Halaesa & Tyndaris and besieged Messana itself: it looked as though he would capture their city.

The Mamertines called for help to both Rome but when that was slow to come they turned to Carthage. The Roman senate hesitated, partly because it felt it improper to support what was virtually a robber-state, and partly because it feared war with a great sea-power, and because interference would be a breach of the treaty which forbade Roman entry into the Sicilian sphere.Left to itself, the senate might have abandoned the Mamertines to their fate. Carthage, evidently expecting this, and encouraged by another faction in Messana, sent their required help. The Carthaginians, arriving first, occupied Messana and effected a reconciliation with Hiero. Some of the Mamertines thought better of this, and requested Roman assistance against the Carthaginians. They sent an embassy to Rome, requesting help to remove the Carthaginian garrison and basing their request on the fact that they were at least fellow-countrymen.

The Mamertines were not Greeks, and could make themselves very useful to Carthage, the traditional enemy of all things Greek. On the other hand, they were of Italian origin, and Rome now stood as the conscious and very efficient protector of all Italian interests. The Mamertines offered themselves and their Sicilian city to the Romans and thereby brought Rome itself to the cross-roads of destiny.