Legio XVIII was a Roman legion levied by Augustus Caesar around 41 BC. The legion was destroyed in the battle of Teutonburg Forest (September 9, 9 AD. The legion's symbol and cognomen are unknown.
This legion was created probably to deal with Sextus Pompeius, the last opponent of the second triumvirate, garrisoned in Sicily and threatening Rome's grain supply. It was probably one of the eight legions Augustus promised Mark Antony for his campaign against the Parthians, but never delivered.
Following the defeat of Antony and Cleopatra in the battle of Actium (31 BC), the legion was stationed in Gaul. In the end of the 1st century BC, the XVIIIth was sent to the Germania provinces in the Rhine to take part in the enormous army led by Drusus, Tiberius and Germanicus. In 5 AD, the provinces were pacified and Publius Quinctilius Varus was assigned governor.
In September 9 AD, Arminius, leader of the Cheruscan allies, reported a rebellion in the Rhine area. Without suspecting the information received, Varus took his three legions, the XVIII along with Legio XVII and Legio XIX, and headed west. In September 9, near modern Osnabrück, the Cheruscii led by Arminius ambushed the governor's. All three legions were destroyed in what is known as the battle of Teutonburg Forest and their eagle standards lost.
Later, Germanicus sent an expedition to the place and recovered the eagles to Rome.