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
Under Augustus, the European borders of the empire he inherited from his grand-uncle Julius Caesar were considerably expanded. During the first half of his sole rule (30–9 BC), Augustus' central strategic objective was to advance the Roman border from Illyricum and Macedonia to the line of the Danube, Europe's greatest river, in order both to increase strategic depth between the border and Italy and to provide a major fluvial supply route for the Roman armies in the region. The strategy was successfully executed: Moesia (29-7 BC), Noricum (16 BC), Raetia (15 BC) and Pannonia (12-9 BC) were annexed in steady succession. After settling the Danube border, Augustus turned his attention to the North, where Julius Caesar had in 51 BC established the border of Roman Gaul along the river Rhine, the second major European fluvial route. Augustus launched an ambitious strategy of advancing the Rhine border to the river Elbe, aiming to incorporate all the warlike Germanic tribes. This would eliminate their chronic threat to Gaul, increase strategic depth between free Germans and Gaul, and make the western Germans' formidable manpower available to the Roman army. But a massive and sustained military effort (6 BC – AD 9) came to nothing. Roman advances in Germania Magna (i.e. Germany outside the empire) had to be scaled down during the Great Illyrian Revolt of AD 6-9, when many troops were diverted to Illyricum. Then Augustus' expansion strategy suffered a crushing setback when some 20,000 Roman troops were ambushed and massacred by the Germans at the Battle of the Teutoburg Forest in AD 9. After this, Augustus shelved his Elbe strategy. It was apparently revived briefly by his successor Tiberius, whose nephews, the generals Germanicus and Drusus, launched major and successful operations in Germania in AD 14-17, during which the main tribes responsible for Varus' defeat were crushed and the three lost legionary "aquilae" (eagle-standards) were recovered.