The armies of Ancient Rome fought three wars with the neighboring Samnite hill tribes; all three ended in Roman victory.

In 343 B.C., the Samnites attacked the Sidicini, who appealed to Campania for help. The strong Samnites made quick work of the Campanians, twice, and then besieged the city of Capua. Even though Rome and the Samnites had been allies, Rome wanted to keep Samnite expansion in check. When the Campanians gave themselves over to Roman influence, Rome sent envoys to the Samnite assembly, beseeching them not to continue their attack. The Samnites refused, and Rome declared war.

Rome at this point was still technically part of the Latin League but, in reality, was the power broker in that confederation of cities, having conquered neighboring Veii and extended its reach south down the coast.

Consul Marcus Valerius Corvus led an army that raised the siege of Capua after the Battle of Mount Gaurus. The other consul, Cornelius Arvina, invaded Samnium and, after narrowly escaping defeat, scored a strong victory over the invaders.

The resilient Samnites quickly gathered another army and set about again into Campania. Valerius again stopped the Samnites cold, at Suessula. The war was, for the most part, over at this point. It officially ended in 341 B.C. with a peace agreement. The Samnites requested only that they be allowed to continue their attack on the Sidicines; Rome, also by this time at war with the Latins, agreed. Campania, however, stayed within the borders of the burgeoning Roman civilization.

The three-year Latin War ended in Roman victory, in 338 B.C., and most of Latium gained citizenship as Romans; some towns remained independent, however.

Rome and the Samnites were at war again 12 years later. The Roman expansion into Campania resulted in escalated tensions between the two powers. The Samnites destroyed the Campanian town of Fregellae and then attacked Romans in Campania again. Rome declared war and, as before, both consuls headed off to war, in 327 B.C. Rome seized a handful of Samnite towns and then won a smashing victory under the dictator Lucius Papirius Cursor in 324 B.C. Rome agreed to the peace plea from the Samnites, who kept the peace for a year but then started the fighting again. Another wide-ranging Roman victory followed, in 322 B.C.; this time, Rome refused the Samnite plea for peace.

The Samnites turned the tables two years later, at a pair of wooded defiles in the Apennine Mountains known as Caudine Forks, as the consuls walked into a trap and suffered the humiliation of surrendering their armies. Those weren't all the soldiers in Rome, and new consuls soon led new armies into battle. Neither side gained much advantage in the next couple of years, and both sides agreed to a truce in 316 B.C.

That truce lasted a short time as well, and the two sides traded victories and city occupations for the next few years. Despite the entry into the war of the Etruscans in 310 B.C., Rome began to turn the tide, establishing new colonies and taking key territory, such as Etruria and Umbria. A final Roman victory in 306 B.C. forced the Samnites to sue for peace and mean it.

Of particular note during the Second Samnite War was the construction of the Appian Way, the first Roman road, and the Aqua Appia, the first aqueduct. Appius Claudius lent his considerable influence to both projects, and the road, especially, made it easier for Rome to move troops quickly to meet new threats.

A short eight years after the end of the Second Samnite War, Rome was again at war with that civilization, which in the new conflict counted as its allies the Etruscans and the Gauls. Beginning in 298 B.C., the Third Samnite War provided Rome–facing a coalition of Etruscans, Gauls, and Samnites–with its greatest challenge yet; Rome, however, was at its strongest and, eight years later, declared victory. Roman armies decisively won the Battle of Sentinum in 295 B.C. and then consolidated their gains for the next half-decade, rolling up Samnite armies and seizing Samnite cities and towns.