Checklist of the Legions
Operational in 68/69
When Augustus set up the principate, he created a standing army whose backbone was constituted eventually by 28 legions of heavy infantry, each numbering supposedly about 5,000 men. Some of the legions traced their origins back to Julius Caesar (most obviously V Alaudae); some were raised in the triumviral period, when the Roman world was carved up by Marc Antony, Marcus Lepidus, and Octavian (Tacitus tells us that III Gallica had served with Antony). And some were new units formed by Augustus after he established the principate. Because of their different origins, and because of the importance the men attached to the records of their units, a consistent, consecutive numbering system was never applied. Numerals were often repeated, and legions with the same number were distinguished by title. So, for example, there were three third legions, one titled Augusta, one Cyrenaica, and one Gallica.
Since Augustus lost 3 legions in the Varian Disaster of 9 (XVII–XIX, numbers never used again), only 25 units remained when he died. By the time Vespasian was recognized as emperor by the senate in December 69 the total had risen to 30. Two new legions were created by Caligula (XV Primigenia and XXII Primigenia), 1 by Nero (I Italica), and 2 by Galba (I Adiutrix and VII Galbiana). There was 1 more unit (I Macriana Liberatrix), the work of Clodius Macer in Africa, but it lasted only for a few months in 68. As emperor, Vespasian disbanded 4 legions that had followed Vitellius (I Germanica, IV Macedonica, XV Primigenia, and XVI), though he incorporated some of the men into 2 new legions, IV Flavia Felix and XVI Flavia Firma (hence their numbering), and he regularized the creation of yet another legion (II Adiutrix), giving a total of 29. For the sake of convenience I have given a brief account of all the units except Vespasian's two new creations, since every one of them turns up sooner or later in the Year of the Four Emperors. Each entry is designedly self-contained, though this has led to some repetition, and where it seems appropriate, I have included specific citations of ancient evidence, especially the Tacitean references to the units or