Brennus (or Brennos) was a chieftain of the Senones. He defeated the Romans at the Battle of the Allia (ca 390 BC). Later that year, he led an army of Cisalpine Gauls in their attack on Rome and captured most of the city, holding it for several months. Brennus's sack of Rome was the only time in 800 years the city was occupied by a non-Roman army before the fall of the city to the Visigoths in 410 AD.