It is considered one of the most important defeats in Roman history, abruptly ending expansion under Augustus. Despite revenge campaigns, the Rhine became the border between the Empire and the rest of Germania.
Based on Wikipedia: Battle of the Teutoburg Forest
Teutoburg Forest is considered one of the most important defeats in Roman history, bringing the triumphant period of expansion under Augustus to an abrupt end.
Retaliatory campaigns were commanded by Tiberius and Germanicus and enjoyed success, but the Rhine became the border between the Roman Empire and the rest of Germania.