Brennus (or Brennos) was a chieftain of the Senones. He defeated the Romans at the Battle of the Allia (18 July 390 BC). In 387 BC 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 the city was occupied by a non-Roman army before the fall of the city to the Goths in 410 AD.