Battle of the Teutoburg Forest in the context of "Aquila (Roman)"

The Roman campaigns in Germania (12 BC – AD 16) were a series of conflicts between the Germanic tribes and the Roman Empire. Tensions between the Germanic tribes and the Romans began as early as 17/16 BC with the Clades Lolliana, where the 5th Legion under Marcus Lollius was defeated by the tribes Sicambri, Usipetes, and Tencteri. Roman Emperor Augustus responded by rapidly developing military infrastructure across Gaul. His general, Nero Claudius Drusus, began building forts along the Rhine in 13 BC and launched a retaliatory campaign across the Rhine in 12 BC.

Drusus led three more campaigns against the Germanic tribes in the years 11–9 BC. For the campaign of 10 BC, he was celebrated for being the Roman who traveled farthest east in northern Europe. Succeeding generals would continue attacking across the Rhine until AD 16, notably Publius Quinctilius Varus in AD 9. During the return trip from his campaign, Varus' army was ambushed and almost destroyed by a Germanic force led by Arminius at the Battle of the Teutoburg Forest; Arminius was the leader of the Cherusci, had previously fought in the Roman army, and was considered by Rome to be an ally. Roman expansion into Germania Magna stopped as a result, and all campaigns immediately after were in retaliation of the Clades Variana ("Varian Disaster"), the name used by Roman historians to describe the Battle of the Teutoburg Forest, and to prove that Roman military might could still overcome German lands. The last general to lead Roman forces in the region during this time was Germanicus, the adoptive son of Emperor Tiberius, who in AD 16 had launched the final major military expedition by Rome into Germania.

The concept of Germany as a distinct region in Central Europe can be traced to Julius Caesar, who referred to the unconquered area east of the Rhine as Germania, thus distinguishing it from Gaul. The victory of the Germanic tribes in the Battle of the Teutoburg Forest (AD 9) prevented annexation by the Roman Empire, although the Roman provinces of Germania Superior and Germania Inferior were established along the Rhine. Following the Fall of the Western Roman Empire, the Franks conquered the other West Germanic tribes. When the Frankish Empire was divided among Charles the Great's heirs in 843, the eastern part became East Francia, and later Kingdom of Germany. In 962, Otto I became the first Holy Roman Emperor of the Holy Roman Empire, the medieval German state.

During the High Middle Ages, the Hanseatic League, dominated by German port cities, established itself along the Baltic and North Seas. The development of a crusading element within German Christendom led to the Northern Crusades and the establishment of the State of the Teutonic Order along the Southern Baltic coast in what would later become Prussia. In the Investiture Controversy, the German Emperors resisted Catholic Church authority. In the Late Middle Ages, the regional dukes, princes, and bishops gained power at the expense of the emperors. Martin Luther led the Protestant Reformation within the Catholic Church after 1517, as the northern and eastern states became Protestant, while most of the southern and western states remained Catholic. The Thirty Years' War, a civil war from 1618 to 1648 brought tremendous destruction to the Holy Roman Empire. The estates of the empire attained great autonomy in the Peace of Westphalia, the most important being Austria, Prussia, Bavaria and Saxony. With the Napoleonic Wars, feudalism fell away and the Holy Roman Empire was dissolved in 1806. Napoleon established the Confederation of the Rhine as a German puppet state, but after the French defeat, the German Confederation was established under Austrian presidency. The German revolutions of 1848–1849 failed but the Industrial Revolution modernized the German economy, leading to rapid urban growth and the emergence of the socialist movement. Prussia, with its capital Berlin, grew in power. German universities became world-class centers for science and humanities, while music and art flourished. The unification of Germany was achieved under the leadership of the Chancellor Otto von Bismarck with the formation of the German Empire in 1871. The new Reichstag, an elected parliament, had only a limited role in the imperial government. Germany joined the other powers in colonial expansion in Africa and the Pacific.

Germania (/dʒərˈmeɪni.ə/ jər-MAY-nee-ə; Latin: [ɡɛrˈmaːni.a]), also more specifically called Magna Germania (English: Greater Germania), Germania Libera (English: Free Germania), or Germanic Barbaricum to distinguish it from the Roman provinces of Germania Inferior and Germania Superior, was a historical region in north-central Europe during the Roman era, which was associated by Roman authors with the Germanic peoples. According to Roman geographers, this region stretched roughly from the Rhine in the west to the Vistula in the east, and to the Upper Danube in the south, and the known parts of southern Scandinavia in the north. Archaeologically, these people correspond roughly to the Roman Iron Age of those regions.

The Latin name Germania means "land of the Germani", but the etymology of the name Germani itself is uncertain. During the Gallic Wars of the 1st century BC, the Roman general Julius Caesar encountered Germani originating from beyond the Rhine. He referred to their lands beyond the Rhine as "Germania". West of the Rhine, the prosperous Roman provinces of Germania Superior and Germania Inferior, sometimes collectively referred to as "Roman Germania", were established in northeast Roman Gaul, while territories east of the Rhine remained independent of Roman control. The Roman emperors also sought to expand east of the Rhine to the Elbe, but these efforts were hampered by the victory of Arminius at the Battle of the Teutoburg Forest in 9 AD.

The 0s began on January 1, AD 1 and ended on December 31, AD 9, covering the first nine years of the Common Era.

In Europe, the 0s saw the continuation of conflict between the Roman Empire and Germanic tribes in the Early Imperial campaigns in Germania. Vinicius, Tiberius and Varus led Roman forces in multiple punitive campaigns, before sustaining a major defeat at the hands of Arminius in the Battle of the Teutoburg Forest. Concurrently, the Roman Empire fought the Bellum Batonianum against a rebelling alliance of native peoples led by Bato the Daesitiate in Illyricum, which was suppressed in AD 9. A conflict also took place in Korea, where Daeso, King of Dongbuyeo invaded Goguryeo with a 50,000-man army in AD 6. He was forced to retreat when heavy snow began to fall, stopping the conflict until the next decade. In China, the last ruler of the Chinese Western Han dynasty (Ruzi Ying) was deposed, allowing Wang Mang to establish the Xin dynasty.

The clades Lolliana or Lollian disaster was a battle in 16 BC, when the consul Marcus Lollius was defeated by the Sicambri, Usipetes and Tencteri, Germanic tribes who had crossed the Rhine. This defeat is coupled by the historian Suetonius with the disaster of Publius Quinctilius Varus in the Battle of the Teutoburg Forest.

After capturing and crucifying Romans in their own lands, the three Germanic tribes crossed the Rhine and plundered Roman territory. Roman cavalry were ambushed and routed. While pursuing the cavalry, the Germani came across the Roman governor Lollius and defeated him as well. They captured the eagle of the fifth legion. When Lollius and Augustus began to assemble armies, the Germani retreated back to their own lands, made peace and gave hostages.

Publius Quinctilius Varus (46 BC or before – September AD 9) was a Roman general and politician. Serving under Augustus, the founder of the Roman Empire, he is generally remembered for having lost three Roman legions in the Battle of the Teutoburg Forest and subsequently committing suicide to avoid capture (and inevitable execution) and shameful reproach. Varus's defeat to the Germanic tribes led by Arminius is considered to be one of the most important events in European history, as it dissuaded the Romans from further expanding into Germania and thus prevented the Romanization of the Germanic peoples to the east of the Rhine.

Arminius (/ɑːrˈmɪniəs/; 18/17 BC–AD 21; Hermann in German) was a chieftain of the Germanic Cherusci tribe who is best known for commanding an alliance of Germanic tribes at the Battle of the Teutoburg Forest in AD 9, in which three Roman legions under the command of general and governor Publius Quinctilius Varus were destroyed. His victory at Teutoburg Forest precipitated the Roman Empire's permanent strategic withdrawal and the deprovincialization of Germania Magna, and modern historians regard it as one of Imperial Rome's greatest defeats. As it prevented the Romanization of Germanic peoples east of the Rhine, it has also been considered one of the most decisive battles in history and a turning point in human history.

Born a prince of the Cherusci tribe, Arminius was part of the Roman-friendly faction of the tribe. He learned Latin and served in the Roman military, which gained him Roman citizenship, and the rank of eques. After serving with distinction in the Great Illyrian Revolt, he was sent to Germania to aid the local governor Publius Quinctilius Varus in completing the Roman conquest of the Germanic tribes. While in this capacity, Arminius secretly plotted a Germanic revolt against Roman rule, which culminated in the ambush and destruction of three Roman legions in the Teutoburg Forest.