The Battle of the Teutoburg Forest ends: The Roman Empire suffers the greatest defeat of its history and the Rhine is established as the border between the Empire and the so-called barbarians for the next four hundred years.

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

The Battle of the Teutoburg Forest, also called the Varus Disaster or Varian Disaster by Roman historians, was a major battle fought between an alliance of Germanic peoples and the Roman Empire between September 8 and 11, 9 AD, possibly near modern Kalkriese. Fighting began with an ambush by the Germanic alliance on three Roman legions being led by Publius Quinctilius Varus and their auxiliaries; the alliance was led by Arminius, a Germanic chieftain and officer of Varus's auxilia. Arminius had received Roman citizenship and a Roman military education, thus allowing him to deceive the Romans methodically and anticipate their tactical responses.

The Roman Empire ruled the Mediterranean and much of Europe, Western Asia and North Africa. The Romans conquered most of this during the Republic, and it was ruled by emperors following Octavian's assumption of effective sole rule in 27 BC. The western empire collapsed in 476 AD, but the eastern empire lasted until the fall of Constantinople in 1453.

The Rhine is one of the major rivers in Europe. The river begins in the Swiss canton of Graubünden in the southeastern Swiss Alps. It forms part of the Swiss-Liechtenstein border, then part of the Swiss-Austrian border. From Lake Constance downstream, it forms part of the Swiss-German border. After that the Rhine defines much of the Franco-German border. It then flows in a mostly northerly direction through the German Rhineland. Finally, the Rhine turns to flow predominantly west to enter the Netherlands, eventually emptying into the North Sea. It drains an area of 185,000 km².