Arminius (German: Hermann; 18/17 BC – AD 21) was a chieftain of the Germanic Cherusci who defeated a Roman army in the Battle of the Teutoburg Forest in 9 AD after betraying the Roman general, of whom he was an auxiliary officer. Arminius's influence held an allied coalition of Germanic tribes together in opposition to the Romans, but after defeats by the Roman general Germanicus, nephew of the Emperor Tiberius, his influence waned, and Arminius was assassinated on the orders of rival Germanic chiefs.