Legio XIII Gemina

Legio XIII Gemina was one of the most celebrated military units of the Roman Army.

It was famous for its pivotal role in Julius Caesar’s rise to power. Formed in 57 BC to fight in the Gallic Wars, this is the legion that marched across the Rubicon River with Caesar in 49 BC, an act of defiance that sparked the Roman Civil War. The 13th remained loyal to Caesar.

Legio XIII was active throughout the entire war, fighting at Dyrrhachium (48 BC) and Pharsalus (48 BC). After the decisive victory over Pompey at Pharsalus, the legion was to be disbanded, and the legionaries "pensioned off" with land grants. The legion was recalled for the Battle of Thapsus (46 BC) and the final Battle of Munda (45 BC). After Munda, Caesar disbanded the legion, retired his veterans, and gave them farmland in their native Italy.

Augustus reconstituted the legion once again in 41 BC to deal with the rebellion of Sextus Pompeius (son of Pompey) in Sicily. Legio XIII acquired the cognomen Gemina ("twin") after being reinforced with veteran legionaries from other legions following the war against Mark Antony and the Battle of Actium. After the disaster of the Battle of the Teutoburg Forest in AD 9, the legion was sent as reinforcements. In the year of the four emperors 69 AD, XIII Gemina supported first Otho and then Vespasian against Vitellius, fighting in the two Battles of Bedriacum. Under Trajan the legion took part in both Dacian wars (101–102, 105–106), and it was transferred by Trajan in 106 to the newly conquered province of Dacia.

Last reports come from the 5th century, where a legio tertiadecima gemina was stationed in Babylon. An archaeological excavation of an elementary school in Vienna in 2024 uncovered bricks bearing the stamp of the 13th Legion Gemina. From the 2nd century, They were likely the broken remnants of pilae stacks, the pillars of brick used to raise the floor for a hypocaust heating system.