Since the reign of the Emperor Augustus, almost the entire Roman army had been placed on the territories along the boundaries of the provinces, though the building of permanent forts only began during the reign of the Emperor Claudius (41-51 A.D.). At the time the legionary fortress at Carnuntum (today´s Bad Deutsch-Altenburg and Petronell, Austria) was set up on the important crossroad of long-distance Amber and Danubian trading routes. Other forts were build on those strategic points where the Roman auxiliary units were placed, e.g. in Arrabona (Győr), Brigetio (Komárom/Szőny), Aquincum (Budapest). However, the systematic construction of the Roman fortifications along the Pannonian frontier started only during the reign of the Flavian Dynasty. The apprehension of Romans of the growing power of the north transdanubian Germanic tribes at that time was reasonable. During the reign of the emperor Domitian (81-96 AD) rise the battles on the middle Danube territory. The Romans were defeated by the Suebi and their allies Sarmatians, who had been occupying the territory east of Danube, by the Tisza river, since the 1^st century AD. These wars definitely ended, not before the reign of the Emperor Nerva (96 – 98 AD) - the successor of Domitian. The unpleasant experience forced the Romans to elaborate new plans for better protection of the Pannonian frontier and strengthen its defence system. More military units were placed along the Danube and a system of fortifications - limes romanus - was build.

During the reign of the Emperor Trajan (98-117 AD) – when the Roman Empire reached its largest extension – other 3 legions were sent to the frontier. The X. legion (gemina) built a fortress in Vindobona (Vienna), the I. auxiliary legion (adiutrix) in Brigetio and the II. auxiliary legion in Aquincum. The Pannonian army was supplemented also by more auxiliary troops. Since the reign of the Emperor Hadrian (117-138 AD), when the number of military units in the province stabilised, the North-Pannonian frontier became to be the most powerful and well armed defence system of the Empire. It was guarded by the three legions, two support troops consisting of 6-7 cavalry, 5 infantry and 2 mixed formations. Their forts (castellum) were build, as a chain fortification system protecting the frontier along the Danube, with the distance of 15-30 kilometres form each other. There were watch-towers (burgi) between some of these forts, creating a control and signal system. The fortification chain was united by a route which was a part of a long distance road connecting the other Danubian provinces. Due to marshy region in the area of inland Danube delta, the limes fortresses and the route system had to swerve south to the Mosony Danube. The defence of the frontier and the distribution of supplies and goods was also duty of the Danube Fleet with number of ports in the area.

Since then, the North-Pannonian frontier belonged to the strongest and the best armed defence system of the Empire. The province, that had played only a secondary role in the beginning, gained the great importance in the 2^nd century AD. The borders of the province were the closest place to the territory of Italia, and the Pannonian army played a key role in the defence of the Empire against the attacks of barbarian tribes during the Marcomannic wars, which ended the relatively peaceful decades of the Antonine period.

The Roman Army

The armament and equipment of the Roman Soldiers

The role and importance of the Roman Army

Marcomannic wars on the Danube

The period of prosperity and decline

The last attempts and the decline of the Roman authority