Legio XIII Gemina, in English the 13th "Twin" Legion was a legion of the Republican, and later Imperial, Roman Army. It was one of Julius Caesar's key units in Gaul and in the civil war, and was the legion with which he crossed the Rubicon in January, perhaps on 10 January, in 49 BC. The legion appears to have still been in existence in the 5th century AD. Its symbol was the lion.
Legio V Macedonica (the Fifth Macedonian Legion) was a Roman legion. It was established in 43 BC by consul Gaius Vibius Pansa Caetronianus and Gaius Julius Caesar Octavianus (later known as the Emperor Augustus). and based in the Balkan provinces of Macedonia, Moesia and Dacia. In the Notitia Dignitatum records from beginning of the fifth century, the legion was still stationed in Dacia, with detachments stationed in the east and Egypt.
The last known evidence shows the legion, or detachments from it, stationed in Egypt in the seventh century one or two years before the Islamic conquest of Egypt. It is often assumed that the legion fought in this war and was destroyed, although it is uncertain whether detachments or the whole legion were in Egypt, and there is no further evidence of the legion's eventual fate.
The phrase "crossing the Rubicon" is an idiom meaning "passing the point of no return". Its meaning comes from the crossing of the Rubicon by Julius Caesar in January 49 BC at the head of the 8th legion. Caesar was not allowed to command an army within Italy proper, and by crossing the river with his forces was defying law and risking death. The crossing precipitated the Roman civil war, which eventually led to Caesar becoming dictator for life (dictator perpetuo).
Caesar had previously been appointed governor of a region that stretched from southern Gaul to Illyricum. As his term was coming to an end, the Senate ordered him to disband his army and return to Rome. Caesar defied the order, and instead brought his army to Rome, occupying the city of Ariminum then crossing the Rubicon towards the south. The exact date of the crossing is unknown, but scholars usually place it on the night of 10 and 11 January because of the speeds at which messengers could travel at that time. The phrase iacta alea est ("the die is cast"), allegedly uttered by Caesar just before the crossing, also comes from this event.
Apulum was a legionary fortress in the Roman province of Dacia from the 2nd to 4th centuries AD, located in today's Alba Iulia, Romania.
It is the largest castrum in Romania, occupying 37.5 hectares (93 acres) (750 x 500 m). It was the base of the legion Legio XIII Gemina transferred there by Trajan to the newly conquered province of Dacia at the end of the war in 106. In the era of Hadrian (117-138 AD) and of Antoninus Pius (138-161 AD) it was rebuilt in stone.