Cisalpine Gaul in the context of Julius Caesar

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 Illyrian Wars were a series of wars fought between the Roman Republic and the Illyrian kingdom under the Ardiaei and Labeatae. In the First Illyrian War, which lasted from 229 BC to 228 BC, Rome's concern was that the trade across the Adriatic Sea increased after the First Punic War at a time when Ardiaei power increased under queen Teuta. Attacks on trading vessels of Rome's Italic allies by Illyrian pirates and the death of a Roman envoy named Coruncanius on Teuta's orders, prompted the Roman senate to dispatch a Roman army under the command of the consuls Lucius Postumius Albinus and Gnaeus Fulvius Centumalus. Rome expelled Illyrian garrisons from a number of Greek cities including Epidamnus, Apollonia, Corcyra, Pharos and established a protectorate over these Greek towns. The Romans also set up Demetrius of Pharos as a power in Illyria to counterbalance the power of Teuta.

The Second Illyrian War lasted from 220 BC to 219 BC. In 219 BC, the Roman Republic was at war with the Celts of Cisalpine Gaul, and the Second Punic War with Carthage was beginning. These distractions gave Demetrius the time he needed to build a new Illyrian war fleet. Leading this fleet of 90 ships, Demetrius sailed south of Lissus, violating his earlier treaty and starting the war. Demetrius' fleet first attacked Pylos, where he captured 50 ships after several attempts. From Pylos, the fleet sailed to the Cyclades, quelling any resistance that they found on the way. Demetrius foolishly sent a fleet across the Adriatic, and, with the Illyrian forces divided, the fortified city of Dimale was captured by the Roman fleet under Lucius Aemilius Paulus. From Dimale the navy went towards Pharos. The forces of Rome routed the Illyrians and Demetrius fled to Macedon, where he became a trusted councillor at the court of Philip V of Macedon, and remained there until his death at Messene in 214 BC.

Italy has been inhabited by humans since the Paleolithic. During antiquity, there were many peoples in the Italian peninsula, including Etruscans, Latins, Samnites, Umbri, Cisalpine Gauls, Greeks in Magna Graecia and others. Most significantly, Italy was the cradle of the Roman civilization. Rome was founded as a kingdom in 753 BC and became a republic in 509 BC. The Roman Republic then unified Italy forming a confederation of the Italic peoples and rose to dominate Western Europe, Northern Africa, and the Near East. The Roman Empire, established in 27 BC, ruled the Mediterranean region for centuries, contributing to the development of Western culture, philosophy, science and art.

During the early Middle Ages, Italy experienced the succession in power of Ostrogoths, Byzantines, Longobards and the Holy Roman Empire and fragmented into numerous city-states and regional polities, a situation that would remain until the unification of the country. These polities and the maritime republics, in particular Venice and Genoa, rose to prosperity. Eventually, the Italian Renaissance emerged and spread to the rest of Europe, bringing a renewed interest in humanism, science, exploration, and art with the start of the modern era. In the medieval and early modern era, Southern Italy was ruled by the Norman, Swabian and Angevin dynasties and the Aragonese, French and Spanish crowns. Central Italy was largely part of the Papal States.

The Roman expansion in Italy covers a series of conflicts in which Rome grew from being a small Italian city-state to be the ruler of the Italian region. Roman tradition attributes to the Roman kings the first war against the Sabines and the first conquests around the Alban Hills and down to the coast of Latium. The birth of the Roman Republic after the overthrow of the Etruscan monarch of Rome in 509 BC began a series of major wars between the Romans and the Etruscans. In 390 BC, Gauls from the north of Italy sacked Rome. In the second half of the 4th century BC Rome clashed repeatedly with the Samnites, a powerful tribal coalition of the Apennine region.

By the end of these wars, Rome had become the most powerful state in central Italy and began to expand to the north and to the south. The last threat to Roman hegemony came during the Pyrrhic War (280–275 BC) when Tarentum enlisted the aid of the Greek king Pyrrhus of Epirus to campaign in the North of Italy. Resistance in Etruria was finally crushed in 265–264 BC, the same year the First Punic War began and brought Roman forces outside of the peninsula for the first time. Starting from the First Punic War (264–241 BC) the territories subject to Roman rule also included Sicily (241 BC), Sardinia and Corsica (238 BC), islands transformed into 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.

The Gauls (Latin: Galli; Ancient Greek: Γαλάται, Galátai) were a group of Celtic peoples of mainland Europe in the Iron Age and the Roman period (roughly 5th century BC to 5th century AD). Their homeland was known as Gaul (Gallia). They spoke Gaulish, a continental Celtic language.

The Gauls emerged around the 5th century BC as bearers of La Tène culture north and west of the Alps. By the 4th century BC, they were spread over much of what is now France, Belgium, Switzerland, Southern Germany, Austria, and the Czech Republic, by virtue of controlling the trade routes along the river systems of the Rhône, Seine, Rhine, and Danube. They reached the peak of their power in the 3rd century BC. During the 4th and 3rd centuries BC, the Gauls expanded into Northern Italy (Cisalpine Gaul), leading to the Roman–Gallic wars, and into the Balkans, leading to war with the Greeks. These latter Gauls eventually settled in Anatolia (contemporary Turkey), becoming known as Galatians.

The Boii (Latin plural, singular Boius; Ancient Greek: Βόιοι) were a Celtic tribe of the later Iron Age, attested at various times in Cisalpine Gaul (present-day Northern Italy), Pannonia (present-day Austria and Hungary), present-day Bavaria, in and around present-day Bohemia (after whom the region is named in most languages; comprising the bulk of today's Czech Republic), parts of present-day Slovakia and Poland, and Gallia Narbonensis (located in modern Languedoc and Provence).

In addition, the archaeological evidence indicates that in the 2nd century BC Celts expanded from Bohemia through the Kłodzko Valley into Silesia, now part of Poland and the Czech Republic.

Cornelius Nepos (/kɔːrˈniːliəs ˈniːpɒs, ˈnɛpɒs/; c. 110 BC – c. 25 BC) was a Roman biographer. He was born at Hostilia, a village in Cisalpine Gaul not far from Verona, or at Ticinum (modern Pavia).

The Insubres or Insubri were an ancient Celtic population settled in Insubria, in what is now the Italian region of Lombardy. They were the founders of Mediolanum (Milan). Though completely Gaulish at the time of Roman conquest, they were the result of the fusion of pre-existing Ligurian and Celtic population (Golasecca culture) with Gaulish tribes.

The War of Mutina (December 44 – April 43 BC; also called the Mutina war) was a civil war between the Roman Senate and Mark Antony in Northern Italy. It was the first civil war after the assassination of Julius Caesar. The main issue of the war was attempts by the Senate to resist Antony's forceful assumption of the strategically important provinces of Transalpine and Cisalpine Gaul from their governors. The Senate, led by Cicero and the consuls (Aulus Hirtius and Gaius Vibius Pansa), attempted to woo Julius Caesar's heir (today known in this period as Octavian) to fight against Antony. Octavian, however, would pursue his own agenda.

The consuls, with Octavian, led troops into northern Italy against Antony and won two battles at Forum Gallorum and Mutina (14 and 21 April 43 BC). After the two consuls were mortally wounded at those battles, there emerged a political vacuum. Octavian – with the support of his men – demanded the consulship from the Senate and marched on Rome. After taking control of the city, Octavian and one of his kinsmen, Quintus Pedius, were irregularly elected consuls. They forced through legislation which had the effect of outlawing Julius Caesar's killers before starting negotiations with Antony. The negotiations resulted in the two men reconciling. With Lepidus, they then formed the Second Triumvirate.

The Battle of the Trebia (or Trebbia) was the first major battle of the Second Punic War, fought between the Carthaginian forces of Hannibal and a Roman army under Sempronius Longus on 22 or 23 December 218 BC. Each army had a strength of about 40,000 men; the Carthaginians were stronger in cavalry, the Romans in infantry. The battle took place on the flood plain of the west bank of the lower Trebia River, not far from the settlement of Placentia (modern Piacenza), and resulted in a heavy defeat for the Romans.

War broke out between Carthage and Rome in 218 BC. The leading Carthaginian general, Hannibal, responded by leading a large army out of Iberia (modern Spain and Portugal), through Gaul, across the Alps and into Cisalpine Gaul (in northern Italy). The Romans went on the attack against the reduced force which had survived the rigours of the march, and Publius Scipio personally led the cavalry and light infantry of the army he commanded against the Carthaginian cavalry at the Battle of Ticinus. The Romans were soundly beaten and Scipio was wounded. The Romans retreated to near Placentia, fortified their camp and awaited reinforcement. The Roman army in Sicily under Sempronius was redeployed to the north and joined with Scipio's force. After a day of heavy skirmishing in which the Romans gained the upper hand, Sempronius was eager for a battle.

The Battle of Lake Trasimene was fought when a Carthaginian force under Hannibal ambushed a Roman army commanded by Gaius Flaminius on 21 June 217 BC, during the Second Punic War. The battle took place on the north shore of Lake Trasimene, to the south of Cortona, and resulted in a heavy defeat for the Romans.

War had broken out between Rome and Carthage early in 218 BC. Hannibal, ruler of the Carthaginian territories in south-east Iberia, marched an army through Gaul, crossed the Alps and arrived in Cisalpine Gaul (northern Italy) later that year. The Romans rushed reinforcements north from Sicily but were badly defeated at the Battle of the Trebia.

Gallia Narbonensis (Latin for "Gaul of Narbonne", from its chief settlement) was a Roman province located in Occitania and Provence, in Southern France. It was also known as Provincia Nostra ("Our Province"), because it was the first Roman province north of the Alps, and as Gallia Transalpina ("Transalpine Gaul"), distinguishing it from Cisalpine Gaul in Northern Italy. It became a Roman province in the late 2nd century BC. Gallia Narbonensis was bordered by the Pyrenees Mountains on the west, the Cévennes to the north, the Alps on the east, and the Gulf of Lion on the south; the province included the majority of the Rhone catchment. The western region of Gallia Narbonensis was known as Septimania. The province was a valuable part of the Roman Empire, owing to the Greek colony and later Roman Civitas of Massalia, its location between the Spanish provinces and Rome, and its financial output.

Brennus (or Brennos) was a Gallic chieftain of the Senones. In c. 387 BC he defeated the Romans at the Battle of the Allia. Later that year, he led an army of Cisalpine Gauls in their attack on Rome and captured most of the city, holding it for several months. Brennus's sack of Rome was the only time in 800 years the city was occupied by a non-Roman army before the fall of the city to the Germanic Visigoths in 410 AD.
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