In 282 BC, the Lucanians and the Bruttians increased their attacks on the Greek colonies of Magna Gracia in south Italy.  The most powerful city-state was Tarentum possessing the most powerful navy of any Italian city.  Heeding calls from the city-states such as Loiri, Rhegim and Thurii, sensing a relatively peaceful mode of entry and support as was their strategy, on 282 BC Rome sent troops by way of sea to Thurii.  Because of a standing treaty, Tarentum considered this move to be an act of aggression and its reaction was to sink the Roman fleet and expel the Roman garrison.
Tarentum then turned to King Pyrrhus of Empirus for help.  King Pyrrhus, buoyed by fresh victories, visualized himself as another Alexander the Great and he looked to Italy as a means to expand his legacy.  Taking his own armies and the Greek Epirotes, he sailed from Sicily across the Adriatic.  The Epirotes were some of the best trained and equipped warriors at the time.  The Epirotes landed in Italy (280 BC) with 25,000 men, including 3,000 cavalry and 2,000 archers.  Pyrrhus also brought 20 war trained elephants.  Pyrrhus thought that the Italian invasion was an excellent opportunity to repeat the success of the elephants in another battle.
The first engagement was in the town of Heraclea.  Under Pubilus Larvinius with 50,000 men, the Roman Legions drove into Lucanian territory to prevent the neighboring tribes from allying with Pyrrhus.  The Roman force might have been destroyed, but was saved by the uncontrollable, wild behavior of a badly wounded elephant.  Although winning, when the rest of the elephants panicked and turned on their own troops, Phyrrhus had to break-off engagement and retreat.  The Romans had lost as many as 10,000 men and the Epirotes some 13,000. 
During the engagement, the Latins in Italy did not rebel attesting to the increasing stability and soundness of The Roman Republic.  Normally, an invading army counts on some of the local tribes rebelling from under their leadership and joining the attractiveness of the invader.  This did not happen for Pyrrhus.
The next year saw the 2nd major conflict with King Pyrrhus at Adsculum.  A massive engagement was fought over two days in the woods and hills of Apulia.  Ox-drawn War Wagons were introduced by the Romans to deter the elephants, but they failed in their purpose.  Taking cover provided by the hills and forests did reduce the effectiveness of the archers and elephants.  Again, there were heavy losses on both sides, which left King Pyrrhus in command of the field, again at great cost.  It was this victory that gave rise to the term, “Pyrrhic Victory” – one more victory like that and I am doomed.
Pyrrhus attempted to negotiate peace terms, but Rome refused as long as he remained in Italy.  By this time Rome had learned that one of its simplest and strongest strategic strengths was perseverance.  In the interim Rome cleverly negotiated an alliance with Carthage which sought protection from Pyrrhus’ army’s resumption of attacks in Sicily.  He sailed to Sicily in 278 BC to defend Greek cities on Sicily.  The Carthagians were already on the move with their besieging of Syracuse.  He eventually defeated the Carthagian army and captured the cities of Panormus and Eryx.  In desperation for revenge, King Pyrrhus returned to Italy in 265 BC and faced the Romans at Malventum in southern Italy.  The Roman Legions had learned how to defend against the elephants by attacking their sides with spears – a tactic that would play a key role against Carthage.  The Pyrrhus’ Epirotes were defeated and surrended at Tarentum.
With Pyrrhus finished, Tarentum and any other Greek city accepted Rome’s lenient offer of peace.  The cities were allowed self-rule under Roman garrisons and appropriate Latin laws.  Additional Roman colonies were founded all over Italy, now including Sicily.
By 272 BC, Rome was now the confirmed master of the Italian peninsula, save for the Gauls in the far north.   Again, the Romans had learned that one of their greatest and simplest, strategic strengths was perseverance.

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