During the fourth century marauding bands of Celts, migrating from their great empire in central Europe, spread terror throughout the peninsulae of southern Europe (pp. 22–3). Various tribes began to pour into Italy. The Insubres entered by the Ticinus valley and defeated the Etruscans near Melpum (Roman Mediolanum and modern Milan), which they captured and settled. Other tribes followed: the Cenomani, Boii, Lingones and Senones. Gradually some advanced over the Po and a few over the Apennines. But they met with a stout resistance from the Etruscans. Naturally the country dwellers submitted easily and the ancient Ligurians, if any survived, were pushed back into the mountains or else were assimilated. But the towns were not so swiftly won. Felsina, for instance, resisted till about 350 and the funeral stelae of the citizens, which depict battle scenes against the Gauls, show the rigour of the struggle. The Etruscan town at Marzabotto also bears witness: the foundations of its buildings are covered with a thick layer of ashes; skeletons and weapons are scattered over its soil. The Veneti succeeded in beating off the attack and retained their independence, but most of the valley of the Po down to the Adriatic shore had succumbed before the end of the fourth century; to the Romans the district became known as Cisalpine Gaul.
These restless Celtic hordes had attained a high level of culture in some respects, but in others they were mere savages. Given to drunkenness, human sacrifices and head-hunting, fickle, adventurous and brave, they rushed naked into battle on foot, on horseback or in chariots; their iron weapons, long swords, high stature, streaming hair and weird cries terrified the disciplined armies of the south when first they appeared. But their staying power and sense of unity were short-lived, as they scattered to plunder or to enjoy their spoil. They were warriors and stock-breeders, impatient of the discipline of agriculture, but with ready adaptability some gradually settled down and became good farmers. In North Italy they eagerly adopted the products of the superior Etruscan civilization and began to till the land, until Cisalpine Gaul became a land of peasants. But some tribes remained on the warpath and in 390 a horde of Senones led by Brennus crossed the Apennines in search of plunder rather than of land and appeared at the gates of Clusium. Etruria was in truth waning. Disunited at home, deprived of Latium and Campania, hard pressed by Rome in the south and now battered by the Gauls in the north, she was at her last gasp. Yet it was Rome that bore the full blast of the storm which threatened to wreck the patient building of a hundred years.
Clusium is said to have appealed for help to the Romans, who despatched envoys to negotiate. These men, however, abandoned their position of strict neutrality and fought shoulder to shoulder with the men of Clusium: one of them even killed a Gallic chief. Thus Rome drew on herself the vengeance of the Gauls. This improbable account seems to have been designed to explain the subsequent defeat of the Romans as divine punishment for the crime of their ambassadors; the appeal made by the barbarians to the ius gentium is ridiculously anachronistic. Nor is it likely that Clusium would appeal to Rome; more probably Diodorus is correct in saying that the Romans heard of the invasion and sent a force to Clusium to reconnoitre. In any case the Gauls abandoned their attack on Clusium and swept like a mountain torrent towards Rome which lay only eighty miles away. Their numbers reached some 30,000. The Romans had only two legions, which inclusive of the cavalry and light-armed troops might number 10,000 men. Even if they were not abandoned by their allies to face the peril alone, as is recorded, they would hardly muster more than 15,000 men; but it was perhaps the greatest army that Rome had yet put into the field. Then dawned that day which ever stood in black letters in the annals of Rome’s history. In the narrow Tiber valley to the north of Fidenae at the eleventh milestone from Rome flowed the little stream of the Allia. Here on the left bank of the Tiber the Romans took up their position. Their left wing was covered by the river, their main force was on the level plain, their right wing of reserves rested on the lower slopes of the Crustuminian mountains. The Gauls swiftly turned the Roman flank by routing the force on the hills and drove the main army back to the Tiber. Here some escaped across the river to Veil, but large numbers were cut to pieces; some of those on the hills may have fled to Rome. Three days later the Gauls arrived at Rome. The priests and the Vestal Virgins had fled to Caere. There was no resistance except in the citadel on the Capitol; the rest of the unresisting city was plundered and burnt.16
At this point legend steps in and relates how the Gauls found the senators who were too old to fight sitting on their ivory seats like gods upon their thrones, awaiting their fate in quiet dignity. Then the survivors at Veii begged Camillus to return from exile at Ardea and to save his country. Pontius Cominius swam the Tiber and reached the Capitol, whence he brought word that the Senate and People of Rome had chosen Camillus dictator. But the Gauls had marked the track of Pontius and would have taken the Capitol by surprise, had not the sacred geese aroused M. Manlius, surnamed Capitolinus, in the nick of time. After a siege of seven months the defenders were forced by famine to offer the Gauls a thousand pounds of gold to withdraw. But even as the gold was being weighed Camillus and his men appeared and drove the Gauls out of the city. This last incident is plainly designed to retrieve Roman honour. The story of Camillus’ exile was perhaps invented to save the conqueror of Veil from blame for the catastrophe and in order that he might be able to rally the survivors outside Rome; doubtless he played a leading part in the story of Rome’s recovery. All that results is that the Romans on the Capitol held out and at length bought off the Gauls, who had attained their object of plundering Rome; it is not likely that they had come to settle, and their departure was hastened by their sufferings from fever and by the fact that their own territory in Cisalpine Gaul was being threatened by the Veneti. The departing guests may even have been speeded on their way by a force of survivors, refugees from Rome and Latin volunteers, who mustered at Veii; but it was the Gauls’ own decision to retire.17
Rome suffered serious internal damage, especially as most of the houses were made of wood; traces of the work of the destructive fire have been found on the Palatine. But the later Romans tended to overestimate the loss, partly from a desire to explain the paucity of early historical documents; in fact the Gauls from superstitious awe may have left untouched some of the temples, where official documents were kept. Soon the city arose fresher and stronger from among her ashes, but the damage to her prestige took longer to heal. Rome’s power in central Italy collapsed, as it had in 509 when the Etruscan dynasty fell; the work of the fifth century had to be repeated in the first half of the fourth. Yet there was another side to the picture; common fear of the Gauls strengthened the idea of unity among the Italians. Finally, it was largely owing to Roman courage in defeat and resolution in rebuilding a barrier against the north that France and not Italy became the home of the Celts.