Sparta's one colony, Tarentum, in Italy, was a wealthy commercial center with a navy, but an inadequate army. When a Roman squadron of ships arrived at the coast of Tarentum, in violation of a treaty of 302 that denied Rome access to its harbor, the Tarentines sank the ships, killed the admiral, and added insult to injury by spurning Roman ambassadors. To retaliate, the Romans marched on Tarentum, which hired soldiers from King Pyrrhus of Epirus (in modern Albania) to help defend it.
Pyrrhus' troops were heavy-armed foot soldiers with lances, a cavalry, and a herd of elephants. They fought the Romans in the summer of 280 B.C. The Roman legions were equipped with (ineffective) short swords, and the Roman cavalry horses couldn't stand against the elephants. The Romans were routed, losing about 7000 men, but Pyrrhus lost perhaps 4000, whom he couldn't afford to lose. Despite his diminished manpower, Pyrrhus advanced from Tarentum to the city of Rome. Arriving there, he realized he had made a mistake and asked for peace, but his offer was rejected.
Soldiers had always come from the propertied classes, but under the blind censor Appius Claudius, Rome now drew troops from citizens without property.
Appius Claudius was from a family whose name was known throughout Roman history. The gens produced Clodius Pulcher (92-52 B.C.) the flamboyant tribune whose gang caused trouble for Cicero, and the Claudians in the Julio-Claudian dynasty of Roman emperors. An evil early Appius Claudius pursued and brought a fraudulent legal decision against a free woman, Verginia, in 451 B.C.
They trained through the winter and marched in the spring of 279, meeting Pyrrhus near Ausculum. Pyrrhus again won by virtue of his elephants and again, at great cost to himself -- a Pyrrhic victory. He returned to Tarentum and again asked Rome for peace.
A couple of years later, Pyrrhus attacked Roman troops near Malventum/Beneventum; this time, unsuccessfully. Defeated, Pyrrhus left with the surviving fraction of the troops he had brought with him.
When the garrison Pyrrhus had left behind in Tarentum departed in 272, Tarentum fell to Rome. In the terms of their treaty, Rome did not require the people of Tarentum to supply troops, as it did with most allies, but instead Tarentum had to provide ships. Rome now controlled Magna Graecia in the south, as well as most of the rest of Italy to the Gauls in the north.
Source: A History of the Roman Republic, by Cyril E. Robinson, NY Thomas Y. Crowell Company Publishers: 1932