In 387 BC the Etruscan city of Clusium woke up to find the barbarian at its gate. "The plight of Clusium was a most alarming one: strange men in thousands were at the gates, men the like of whom the townsfolk had never seen, outlandish warriors armed with strange weapons, who were rumoured to have already scattered the Etruscan legions on both sides of the Po; it was a terrible situation..." (Livy)

As matters stood in Italy at the time, Etruscan power had begun to wane, and the new star in the ascendant was the city of Rome, not yet the great power that it would later become, but rapidly expanding its sphere of influence. An army of Senones and associated Celtic tribes from north of the Apennines had begun to move south through Italy from about 400 BC, on a famous campaign that would culminate in the sack of Rome... and the city of Clusium stood in the way of their advance.

The city fathers immediately appealed to Rome for help, forgetting their old differences with their rival city in the face of the immediate Celtic threat. Rome responded by sending three envoys, brothers from the ancient house of the Fabii, to remonstrate with the Celts and their leader Brennus, a chieftain of the Senones. Diodorus Siculus says the Fabii were really spies, sent by Rome to assess the strength of the Celtic army. Whatever, their intervention certainly served to exacerbate matters. When the envoys demanded by what right the Gauls were in Etruria, the Celts replied: "... all things belong to the brave who carry justice on the points of their swords". A fight promptly broke out and the Roman envoys killed one of the Celtic chieftains. On their return to Rome, the envoys were promoted to military tribuneships... whereon the Celts immediately broke off the siege of Clusium, and turned their vengeful attention to Rome itself:

"The Gauls... flamed into the uncontrollable anger which is characteristic of their race, and set forward, with terrible speed, on the path to Rome. Terrified townships rushed to arms as the avengers went roaring by; men fled from the fields for their lives; and from all the immense host, covering miles of ground with its straggling masses of horses and foot, the cry went up 'To Rome!' . . . The sheer speed of the Gallic advance was a frightful thing . . . the air was loud with the dreadful din of the fierce war-songs and discordant shouts of a people whose very life is wild adventure."

Rome hastily assembled an army under the command of A.Quintus Sulpicius and despatched it to meet the Celtic advance. On 18th July Brennus and his Celtic warriors met the Romans for the first time, on the banks of the River Allia about 10-12 miles north of the city itself, and smashed their way through Sulpicius’s army:

"... the main body of the army, at the first sound of the Gallic war-cry on their flank and in their rear, hardly waited even to see their strange enemy from the ends of the earth; they made no attempt at resistance; they had not even courage to answer his shouted challenge, but fled before they had lost a single man."

Many were drowned in the river, a few escaped to the nearby city of Veii, and only a handful made it back to Rome, "where without even closing the gates behind them, they took refuge in the Citadel."

Rome was in a panic- the city was largely indefensible and lay open to the Celts: only the Capitoline Hill was barricaded and defended. Brennus and his army arrived at the gates of the city three days after the battle at the river, to find the gates open and the city apparently largely deserted. There he hesitated, fearing some kind of ambush or trick, but then the Celts began to advance through the city, burning and looting as they went. Livy now tells one of those anecdotal stories he littered his "History" with: when they reached the Forum there they found the aged senators of the city, who had elected to remain behind when everyone else fled to the Capitoline, clad in their official robes and waiting calmly and gravely for their certain deaths. "They might have been statues in some holy place, and for a while the Gallic warriors stood entranced; then on an impulse one of them touched the beard of a certain Marcus Papirus, and the Roman struck him on the head with his ivory staff." Naturally, the outraged Gaul promptly killed him, and all the senators were massacred before the barbarians recommenced their looting and burning, and laid siege to the Capitoline Hill.

In the Capitoline, the Romans were in a good defensive situation, and despite the attempt of the Celts to sneak into the Capitoline by night, which was thwarted by the timely cackling of the sacred geese in the temple of Juno, they managed to hold out. The siege dragged on for six months. By then, the Roman garrison was suffering greatly from lack of supplies, and even the besieging Celtic army was beginning to feel the misery:"The Gauls had disease as well to contend with... the heat stifled them, infection spread, and they were soon dying like cattle."

They weren’t so miserable however that they would agree to lift the siege without a considerable ransom being paid to them: a compromise was reached whereby they would withdraw on payment of 1,000 lb of gold.

"Quintus Sulpicius conferred with the Gallic chieftain Brennus and together they agreed upon the price, one thousand pounds' weight of gold -- the price of a nation soon to rule the world. Insult was added to what was already sufficiently disgraceful, for the weights which the Gauls brought for weighing the metal were heavier than standard, and when the Roman commander objected the insolent barbarian flung his sword into the scale, saying 'Vae Victis-- 'Woe to the vanquished!' "

At this point, according to the fiercely patriotic and propagandist Livy, M. Furius Camillus, who had hastily been elected Dictator while he was in exile and recalled to save his city, suddenly materialized on the scene with a Roman army from Ardea. He declared the agreement null and void and drove the Celts out of the city. On the following day the two armies met outside the city and Camillus slew Brennus. This was probably wishful thinking on Livy’s part however, as Polybius and Diodorus Siculus, drawing upon older and less biased sources, seem to give a truer picture: "The Celts withdrew unmolested with their booty, having voluntarily and on their own terms restored the city to the Romans."

Anticlimax? Not really. When the dust had settled behind the withdrawing Celts, Rome was left a shambles. Internal civil strife reigned for the next twenty years, during which time the Celts continued to harass the city. Eventually in 345 BC they entered into a formal treaty with Rome, a treaty which was kept to only for the space of thirty years...