The first invaders to sack Rome were a Germanic people called the Visigoths, who were lead by a 20-year-old chieftain named Alaric. The sacking of Rome occurred in the middle of the night in 410 A.D. when disgruntled slaves opened the Salarian Gate, which gave the Visigoths the element of surprise.
Alaric first started attacking the Roman Empire in Italy and in the Balkans between 400 A.D. and 409 A.D., but was mostly unsuccessful at the time. He continued his attack on Rome once again in 409 A.D., and was successful in installing a temporary emperor named Priscus Atallus. Alaric's final attack on Rome in 410 A.D. was the result of the authorities in the Roman city of Ravenna, who refused to give Alaric and his people land that they could settle on.