While the southern Illyrian province and its peaceful government soon ceased to be prominent in a historical aspect, northern Illyricum, or as it is usually called, Pannonia, forms in the imperial period one of the great military and thereby also political centres. In the army of the Danube the Pannonian camps have the leading position like the Rhenish in the west, and the Dalmatian and the Moesian attach themselves to them, and subordinate themselves under them, in like manner as the legions of Spain and Britain were subordinate to those of the Rhine. Roman civilisation stands and continues here under the influence of the camps, which did not remain in Pannonia as in Dalmatia only for some generations, but were permanent. After the subduing of the insurrection of Bato, the regular garrison of the province amounted at first to three, afterwards apparently only to two, legions; and the further development was conditioned by their standing quarters and the shifting of these forward. When Augustus after the first war against the Dalmatians had selected Siscia, at the point where the Kulpa falls into the Save, as his chief stronghold, after Tiberius had subdued Pannonia at least as far as the Drave, the camps were pushed forward to the latter, and at least one of the Pannonian headquarters was thenceforth found at Poetovio (Pettau), on the borders of Noricum. The reason why the Pannonian army remained wholly or in part in the valley of the Drave can only have been the same as led to the construction of the Dalmatian legionary camps; they needed troops here to keep in obedience their subjects as well in the neighbouring Noricum as above all in the region of the Drave itself. On the Danube watch was kept by the Roman fleet, which is already mentioned in the year 50, and presumably originated on the erection of the province. There was not yet perhaps a legionary camp on the river itself under the Julio-Claudian dynasty,[119] in connection with which we may note that the state of the Suebi immediately adjoining the province in front was at that time immediately dependent on Rome, and sufficed in some measure to protect the frontier. Then, as with the camps of Dalmatia, Vespasian apparently did away also with the camps on the Drave and transferred them to the Danube itself; thenceforth the great headquarters of the Pannonian army were the formerly Norican (p. 198) Carnuntum (Petronell, to the east of Vienna), and along with it Vindobona (Vienna). [Sidenote: Urban development.]