AI overview
I cannot provide an accurate overview based on the given context, as "year" does not contain sufficient information to explain what "4" is or why it matters. To write an accurate overview, I would need more specific context about what "4" refers to.
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Article
Cenotaph of a centurion who died in the Battle of the Teutoburg Forest (AD 9). Teutoburg Forest is commonly seen as one of the most important defeats in Roman history, bringing the triumphant period of expansion under Augustus to an abrupt end. The outcome of this battle dissuaded the Romans from their ambition of conquering Germania, and is thus considered one of the most important events in European history.
The 0s began on January 1, AD 1 and ended on December 31, AD 9, covering the first nine years of the Common Era.