Socii in the context of "Social War (91–87 BC)"

Roman Italy is the period of ancient Italian history going from the founding and rise of Rome to the decline and fall of the Western Roman Empire; the Latin name of the Italian peninsula in this period was Italia (continued to be used in the Italian language). According to Roman mythology, Italy was the ancestral home of Aeneas, being the homeland of the Trojans progenitor, Dardanus; Aeneas, instructed by Jupiter, moved to Italy after the fall of Troy, and his descendants, Romulus and Remus, were the founders of Rome. Aside from the legendary accounts, Rome was an Italic city-state that changed its form of government from Kingdom (ruled, between 753 BC and 509 BC, by seven kings) to Republic, and then grew within the context of a peninsula dominated by the Gauls, Ligures, Veneti, Camunni and Histri in the North; the Etruscans, Latins, Falisci, Picentes, Umbri and Sabines in the Centre; and the Iapygian tribes (such as the Messapians), the Oscan tribes (such as the Samnites) and Greek colonies in the South.

The consolidation of Italy into a single entity occurred during the Roman expansion in the peninsula, when Rome formed a permanent association with most of other the local tribes and cities; and Italy's inhabitants included Roman citizens, communities with Latin Rights, and socii. The strength of the Italian confederacy was a crucial factor in the rise of Rome, starting with the Punic and Macedonian wars between the 3rd and 2nd century BC. As Roman provinces were being established throughout the Mediterranean, Italy maintained a special status with political, religious and financial privileges. In Italy, Roman magistrates exercised the imperium domi (police power), as an alternative to the imperium militiae (military power) exercised in the provinces.

The Second Punic War (218 to 201 BC) was the second of Punic Warsthree wars fought between Carthage and Rome, the two main powers of the western Mediterranean in the 3rd century BC. For 17 years the two states struggled for supremacy, primarily in Italy and Iberia, but also on the islands of Sicily and Sardinia and, towards the end of the war, in North Africa. After immense materiel and human losses on both sides, the Carthaginians were once again defeated. Macedonia, Syracuse and several Numidian kingdoms were drawn into the fighting, and Iberian and Gallic forces fought on both sides. There were three main military theatres during the war: Italy, where Hannibal defeated the Roman legions repeatedly, with occasional subsidiary campaigns in Sicily, Sardinia and Greece; Iberia, where Hasdrubal, a younger brother of Hannibal, defended the Carthaginian colonial cities with mixed success before moving into Italy; and Africa, where Rome won the war.

The First Punic War had ended in a Roman victory in 241 BCE after 23 years and enormous losses on both sides. After the war Carthage expanded its holdings in Iberia where in 219 BCE a Carthaginian army under Hannibal besieged, captured and sacked the pro-Roman city of Saguntum. In spring 218 BC Rome declared war on Carthage, beginning the Second Punic War. Later that year, Hannibal surprised the Romans by marching his army overland from Iberia, through Gaul and over the Alps to Cisalpine Gaul (modern northern Italy). Reinforced by Gallic allies he obtained crushing victories over the Romans at the battles of Trebia (218) and Lake Trasimene (217). Moving to southern Italy in 216 Hannibal defeated the Romans again at the battle of Cannae, where he annihilated the largest army the Romans had ever assembled. After the death or capture of more than 120,000 Roman troops in less than three years, many of Rome's Italian allies, notably Capua, defected to Carthage, giving Hannibal control over much of southern Italy. As Syracuse and Macedonia joined the Carthaginian side after Cannae, the conflict spread. Between 215 and 210 BC the Carthaginians attempted to capture Roman-held Sicily and Sardinia, but were unsuccessful. The Romans took drastic steps to raise new legions: enrolling slaves, criminals and those who did not meet the usual property qualification; this vastly increased the number of men they had under arms. For the next decade the war in southern Italy continued, with Roman armies slowly recapturing most of the Italian cities that had joined Carthage.

Foederati (/ˌfɛdəˈreɪtaɪ/ FED-ə-RAY-ty; singular: foederatus /ˌfɛdəˈreɪtəs/ FED-ə-RAY-təs) were peoples and cities bound by a treaty, known as foedus, with Rome. During the Roman Republic, the term identified the socii, but during the Roman Empire, it was used to describe foreign states, client kingdoms or barbarian tribes to which the empire provided benefits in exchange for military assistance. The term was also used, especially under the empire, for groups of barbarian mercenaries of various sizes who were typically allowed to settle within the empire.

The March on Rome of 88 BC was a coup d'état by the consul of the Roman Republic Lucius Cornelius Sulla, who seized power against his enemies Marius and Sulpicius, after they had ousted him from Rome. It was the first time in Roman history that a general ordered his army to march against the Republic.

In 88 BC, Sulla was elected consul and given the command of the war against the king of Pontus Mithridates, who had recently invaded the Roman province of Asia. The same year, Sulla and his colleague Quintus Pompeius Rufus opposed the attempt of the tribune of the plebs Publius Sulpicius to enrol the Italians who received the Roman citizenship at the end of the Social War (91–87 BC). To bypass the consuls' opposition, Sulpicius sought the support of the popular Gaius Marius, who had already been consul six times. Marius demanded for his help that Sulpicius pass a law transferring Sulla's command to him. Using armed gangs to intimidate the tribal assembly, Sulpicius removed Pompeius' consulship and forced Sulla to flee from Rome, after which he enrolled the Italians and gave the Mithridatic command to Marius.

The Pyrrhic War (/ˈpɪrɪk/ PIRR-ik; 281–275 BC) was a conflict fought by Pyrrhus of Epirus and his allies against the Roman Republic, supported by its allies, and Carthage. Fought mainly in Magna Graecia and Sicily, Pyrrhus first intervened at the invitation of the Italiote Greeks against Roman expansion. However, his aims in the war became oriented towards establishing hegemony over southern Italy and Sicily. Initially meeting some success, his aims were left unfulfilled after his campaign in Sicily stalemated against Carthaginian resistance and Rome forced his withdrawal from Italy in 275 BC. The first major conflict involving Rome and one of the Hellenistic powers, Rome's victory showed its emergence as a major Mediterranean power.

Prior to the war, the Romans had expanded for some decades into southern Italy, defeating most notably the Samnites. They also started to conclude alliances with the Greek city-states of Magna Graecia. The outbreak of a new conflict between one of those allies, Thurii, and a Samnite-led alliance led to Roman intervention. The Tarentines, seeking to prevent continued Roman intervention in southern Italy, attacked a Roman fleet sailing in their waters contrary to a previous treaty and marched on Thurii, deposing the pro-Roman government there. After rejection of a Roman ultimatum in early 281 BC, war was declared. Cognisant of their weakness in the field, the Tarentines sought foreign support in the form of Pyrrhus of Epirus, who landed at Tarentum with reinforcements in the winter of 281/80 BC.

The Battle of Cannae (/ˈkæni, -eɪ, -aɪ/; Latin: [ˈkanːae̯]) was a key engagement of the Second Punic War between the Roman Republic and Carthage, fought on 2 August 216 BC near the ancient village of Cannae in Apulia, southeast Italy. The Carthaginians and their allies, led by Hannibal, surrounded and practically annihilated a larger Roman and Italian army under the consuls Lucius Aemilius Paullus and Gaius Terentius Varro. It is regarded as one of the greatest tactical feats in military history and one of the worst defeats in Roman history, and it cemented Hannibal's reputation as one of antiquity's greatest tacticians.

Having recovered from their losses at Trebia (218 BC) and Lake Trasimene (217 BC), the Romans decided to engage Hannibal at Cannae, with approximately 86,000 Roman and allied socii troops. They massed their heavy infantry in a deeper formation than usual, while Hannibal used the double envelopment tactic and surrounded his enemy, trapping the majority of the Roman army, who were then slaughtered. Later historians and military strategists have used Cannae as an exemplary battle of annihilation. The loss of life on the Roman side meant it was one of the most lethal single days of fighting in history; historian Adrian Goldsworthy equates the death toll at Cannae to "the massed slaughter of the British Army on the first day of the Somme offensive in 1916". Only about 15,000 Romans, most of whom were from the garrisons of the camps and had not taken part in the battle, survived. Following the defeat, Capua and several other Italian city-states defected from the Roman Republic to Carthage.