Slovakia in the Roman era
The reign of Augustus (27 BC - 14 AD) began a long period known as the Pax Romana, or Roman peace. Despite continuous wars on the frontiers, and one year-long civil war over the imperial succession, the Mediterranean world remained at peace for more than two centuries. Augustus enlarged the empire dramatically, annexing Egypt, Dalmatia, Pannonia, and Raetia, expanded possessions in Africa, and completed the conquest of Hispania.
By the end of his reign, the armies of Augustus had conquered the Alpine regions of Raetia and Noricum (modern Switzerland, Bavaria, Austria, Slovenia), Illyricum and Pannonia (modern Albania, Croatia, Hungary, Serbia, etc.).
Imperial Roman army
On gaining undisputed mastery over the Roman empire in 30 BC, Augustus (sole rule 30 BC – AD 14) was left with an army which was bloated by extraordinary recruitment for the Roman civil wars and at the same time lacking a suitable organisation for the defence and expansion of a vast empire. Even after disbanding most of his defeated adversary Mark Anthony's legions, Augustus had 50 legions under his command, composed exclusively of Roman citizens i.e. by that time, of Italians and inhabitants of Roman colonies outside Italy. Alongside these were a mass of irregular non-Italian allied units whose command, size and equipment varied greatly. Some allied units came from provinces within the empire, others from beyond the imperial borders.