The campaigns began successfully under Nero Claudius Drusus (12–9 BC), who pushed deep into Germanic territory, reaching the Elbe river. Following Drusus's sudden death in 9 BC after a fall from his horse, his brother Tiberius—the future emperor—continued the pacification. By 6 AD, Germania seemed poised to become a Roman province.
However, in 9 AD, disaster struck. Publius Quinctilius Varus, the governor of Germania, was betrayed by Arminius, a Roman-educated chieftain of the Cherusci. Arminius led three Roman legions into an ambush in the Teutoburg Forest, annihilating them completely. It was one of the worst defeats in Roman history, allegedly causing Augustus to bang his head against a wall, crying, 'Varus, give me back my legions!'
Rome retaliated with punitive campaigns led by Germanicus (14–16 AD), defeating Arminius at Idistaviso and recovering the lost legionary eagles. However, after the death of Augustus in 14 AD, his successor Tiberius adopted a more cautious foreign policy. Despite Germanicus's victories, Emperor Tiberius decided that conquering Germania was too costly and dangerous. He recalled Germanicus and established the Rhine as the permanent boundary of the empire.