The Gaul invasion

Rome was one of the most important powers, when in 387 b.C. the Senons a Gallic tribe crossed the Appennines and approached the town. The Romans tried to stop them vainly; but, frightened by the their horned helmets, and savage beards, they were easily defeated. The Gauls entered the city and destroyed it.
Only a few Roman warriors, retreated to the Capital and continued to resist, but a few days later, hunger forced the valiant defensors of the Capitol to come to terms (see the legend of the Capitoline Geese).
Rome had to buy its freedom with gold, a lot of gold which was weighed with balances, on which the Gaul leader Brenno had put his sword.
Fortunately at the same time, Camillo a valiant Roman general was coming back to Rome, and had gathered all the warriors.
He arrived in front of Brenno in a fury shouting that Rome would have been liberated with iron and not with gold. That was the sign of revenge. Romans took up arms again, and threw out the Gauls. Even if Rome had been nearly destroyed, it was free. Camillo rebuilt it more magnificently, and for this reason he was called the Second Founder of Rome .