Over the course of nearly four centuries, theRoman Republic fought a series of wars against variousCeltic tribes, whom they collectively described asGalli, orGauls. Among the principal Gallic peoples described as antagonists by Greek and Roman writers were theSenones,Insubres,Boii, andGaesatae.

The Romans first came into conflict with Gauls who entered Italy from the north. Some of these settled in the lands immediately south of the Alps, which became known asCisalpine Gaul: "Gaul this side of the Alps". Gaulish armies, some perhaps fighting as mercenaries in the service of the cities ofMagna Graecia, plundered territory inEtruria andLatium during the fourth century, famously sacking Romecirca 390 BC.^[1]

Following theSamnite Wars and thePunic Wars, in which Gallic forces sometimes made common cause with Rome's enemies, the Romans found themselves in near-total control of Italy, including Cisalpine Gaul. As they consolidated their gains, they came into conflict with Gallic tribes on the borders of their growing empire, and subsequent conflicts occurred in and beyond the Alps. In the first century BC,Caesar'scampaigns in Gaul brought most of the Gallic territory in western Europe under Roman control.^[2]

Major conflicts on the Italian side of the Alps include:

390^[i] BC:Brennus leads the Senones toClusium in Etruria. Rome sends an army to drive the Senones away, which the Senones defeat at theBattle of the Allia. Brennus leads his men on to Rome, entering the city without further opposition, and plundering it. They depart laden with booty, which according to varying traditions was recovered when the Gauls were defeated by aCaeretan army, or byCamillus.^{[4][5][6][7][1][8][9]}

367 BC: A Gallic expedition is said to have been routed by Camillus, but the historicity of this episode is doubtful.^{[10][11][12][13]}

361–358 BC: Gauls allied withTibur attack Roman territory during that city's war with Rome.Titus Manlius Imperiosus wins the surnameTorquatus after defeating a Gaulish champion in single combat, and taking historque as a trophy.^[14][15][13]

350–349 BC: The Gauls ravage Latium, and theLatin League refuses direct aid to Rome. Despite various hardships, the Romans defeat their attackers, and a youngMarcus Valerius Corvus wins everlasting fame by slaying a giant Gaul in single combat, aided by a raven, from which he takes his surname.^{[16][17][18][19][20]}

331 BC: The Romans conclude a peace with the Gauls, which holds for nearly thirty years.^[21][22]

302 BC: Gauls cross the Alps into Cisalpine Gaul, where previously-settled Gallic tribes allow them to pass southward. Some of the latter join the march, as do someEtruscans. They pillage Roman territory and retire with the loot, but then fall to fighting among themselves.^[23]

295 BC: During theThird Samnite War, an alliance ofSamnites, Gauls, Etruscans andUmbrians fights Rome. After an initial defeat, the Romans win a major victory at theBattle of Sentinum under the consulsQuintus Fabius Maximus Rullianus andPublius Decius Mus, whodevotes himself and perishes in the battle.^[23][24][25]

284 BC:^[26] The Gauls besiegeArretium. The Romans march to relieve the city, and the Gaulsdefeat them. Rome then sends a punitive expedition north which defeats the Senones and drives them out of their territory, which Rome occupies.^[23] Then in 283 BC the Boii, with Etruscan allies, march on Rome.^[27] Rome is victorious at theBattle of Lake Vadimo.^{[28][29][30][9]}

225 BC: The Insubres and Boii hire Alpine Gauls, the Gaesatae, to join them and march on Rome. The Gauls defeated the Romans atFaesulae, but later the Romans defeated the Gauls atTelamon.^[31][32][33]

223–193 BC: After this came a concerted Roman policy aimed at conquering Gallic territories south of the Alps. Rome invaded the territory of the Insubres in 223 BC, and tookClastidium,Acerrae andMediolanum in 222 BC.^[34][35][36] Rome foughtCarthage in theSecond Punic War (218–201 BC), and the Gauls typically sided with Carthage.^[36] After the war, Rome tookBononia (196 BC),^[37][38]Placentia (194 BC),^[39][40][36] andMutina (193 BC).^[41][42] According to Strabo, many of the surviving Boii retreated north across the Alps to the land subsequently known asBoihaemum,^[43] but in all probability the region was already inhabited by Boii prior to their subjugation in Italy.^[44]

125–121 BC: Romans crossed the Alps and fought first theSalluvii andVocontii,^{[45][46][47][48]} and thenAllobroges andArveni. The Gauls were decisively defeated at theBattle of Vindalium andBattle of the Isère River in 121 BC.^[49][50][51] The Allobrogian territory was subsequently annexed and incorporated the Roman province known as Gallia Transalpina, laterGallia Narbonensis.^[52][53]

109 BC: During theCimbrian War, theCimbri defeat the consulMarcus Junius Silanus.^[54][55] in 107 BC, the Cimbri andAmbrones, together with their allies Helvetii, defeat a Roman army near Agendicum in theBattle of Burdigala, in which the consulLucius Cassius Longinus is killed.^{[56][54][57][58][59]}

58–50 BC:Caesar leads a series ofcampaigns through Gaul, which he chronicles in detail. The result is the near-complete subjugation of the country between the Atlantic and the Rhine. After discovering that some of the Gauls are receiving aid from Britain, Caesar mounts the first Roman military expedition to that island.^[60][61][2]

40–37 BC: Prompted by unrest in Gaul,Marcus Vipsanius Agrippa marches against theAquitani, whom he defeats.^[62][63]

28–27 BC:Marcus Valerius Messalla Corvinus suppresses a revolt inAquitania, for which he celebrates atriumph.^[64][65]

• Polybius,Historiae (The Histories).
• Marcus Tullius Cicero,Pro Fonteio.
• Gaius Julius Caesar,Commentarii de Bello Gallico (Commentaries on the Gallic War).
• Diodorus Siculus,Bibliotheca Historica (Library of History).
• Dionysius of Halicarnassus,Romaike Archaiologia (Roman Antiquities).
• Titus Livius (Livy),History of Rome.
• Strabo,Geographica.
• Publius Cornelius Tacitus,De Origine et Situ Germanorum (The Origin and Situation of the Germans, or "Germania").
• Appianus Alexandrinus (Appian),Bella Celtica (The Gallic Wars);Bellum Civile (The Civil War).
• Dictionary of Greek and Roman Geography,William Smith, ed., Little, Brown and Company, Boston (1854).
• T. Robert S. Broughton,The Magistrates of the Roman Republic, American Philological Association (1952–1986).
• Oxford Classical Dictionary, Second Edition, N. G. L. Hammond and H. H. Scullard, eds., Clarendon Press, Oxford (1970).
• Timothy J. Cornell,The Beginnings of Rome: Italy and Rome from the Bronze Age to the Punic Wars (c. 1000–264 BC), Routledge, London (1995).

• 4th-century BC conflicts
• 3rd-century BC conflicts
• 2nd-century BC conflicts
• 1st-century BC conflicts
• 4th century BC in the Roman Republic
• 3rd century BC in the Roman Republic
• 2nd century BC in the Roman Republic
• 1st century BC in the Roman Republic
• Wars involving the Celts
• Pre-Roman Gaul
• Wars involving the Roman Republic

• Articles with short description
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