Legio I Germanica, ( First Legion "Germanic"), was a legion of the Imperial Roman army, possibly founded in 48 BC by Julius Caesar to fight for him in the civil war against Pompey. The title germanic is a reference to its service in the Germanic Wars, rather than the place of origin of its soldiers. After the Revolt of the Batavi (AD 70), the remaining men of the Germanica were added to Galba's seventh legion, which became VII Gemina. The emblem of Legio I is unknown, but it was probably Taurus, like all the other legions levied by Caesar (except the V Alaudae).
Origin
There are three theories about I Germanica recruitment. The most favored is that it was raised by Julius Caesar in 48 BC to fight in the civil war against Pompey. The Legion first saw action at the Battle of Dyrracchium. In that case it would have fought in the Battle of Pharsalus in 48 BC. Another claim is that the legion was raised by Pompey and it fought against Caesar and Pharsalus, Thaspus, and Munda.
The third theory attributes its recruitment to Gaius Vibius Pansa Caetronianus, a partisan of Caesar, who died in the Battle of Forum Gallorum against Mark Antony in 43 BC. Legio I would have been recruited in that year for that campaign.
However recruited, Legio I was inherited by Augustus and therefore ought to have been entitled to the cognomen Augusta after distinguished service under his eyes; however, there was no Legio I Augusta. That title was stripped after a defeat in the Cantabrian wars and the loss of its standard to the Astur and Cantabrian peoples.
The legion would fight against Sextus Pompey in Sicilly in 36 BCE. After Augustus loses a battle, he requested the Legio I Germanica as reinforcements.
Hispania disgrace
After the civil war the legion joined the army of Augustus. It is believed to be identical to the Legio I that took part in the Hispania campaign against the Cantabri conducted for Augustus by Marcus Agrippa and was disgraced there. Inscriptions on coins from Hispania indicate that between 30 and 16 BC, some Legio I was stationed in Hispania Tarraconensis, where they would have fought in the war against the Cantabrians and Asturians. Dio Cassius (54.11.5) says that one legion was stripped of its title, Augusta, after suffering reverses in that campaign. The two references are believed to be to the same legion, accounting for its early missing title and emblem. While in Spain they helped build the colonia Acci.
Distinguished service in Germania
Around the turn of the century, Legio I appears on the Rhine frontier. They may have been moved to the Rhine in order to help emperor Tiberius's war against the Vindelicia. The Annales of Tacitus state that they received standards from Tiberius, but when that was is not clear. This statement is problematic because only new or reconstituted legions received standards. Other theories suggest they received the standard after winning a battle near Lake Constance. Because of their service in Germania the legion soon redeemed itself, winning the title Germanica for it. Exactly when they won it is not known. Most likely, the title Germanica was granted for service in Drusus' subsequent punitive and exploratory campaigns against the Germanic tribes. Drusus was extremely popular. It was an honor to be in his service and he made sure that his men were honored properly.
Mutiny on the Limes Germanicus
After the defeat of Varus, Augustus' adoptive son Tiberius (brother of Drusus) assumed command of the army on the Rhine, which was reinforced to eight legions. When Tiberius returned to Italy in 13 AD, Augustus appointed Drusus' son, Germanicus, commander of the eight legions on the Rhine. In the following year Augustus died, Tiberius being his successor.
Subsequently Junius Blaesus, commander of three legions in summer camp in Pannonia, gave the men a holiday. A soldier who had been a claqueur, Percennius, addressed the men on that occasion on the subject of soldier's benefits. They needed a fixed contract, he said, a term of service of 16 seasons instead of 25 or 30, and a pay raise. The speech was far from comic. The men as he spoke began raise a dais of earth around him and brought the standards and that attracted the attention of the Praetor, Blaesus. Unable to dissuade the men, he agreed to send his son, a tribune, to Tiberius with the demands. The men settled down to await the reply.