In early September AD 9, a four-day battle in the remote Teutoburg Forest of northern Germania left half of Rome’s western army destroyed. Three entire legions under the command of the veteran commander Publius Quinctilius Varus, three cavalry units and six auxiliary regiments—fully 25,000 men—were ambushed and wiped out, stopping the expansion of the Empire in northern Europe dead in its tracks.

Suetonius reports that the battle’s outcome left Augustus (then aged 71) despondent:

…he was so greatly affected that for several months in succession he cut neither his beard nor his hair, and sometimes he would dash his head against a door, crying: “Quintilius Varus, give me back my legions!” And he observed the day of the disaster each year as one of sorrow and mourning.
[Suetonius, Augustus, 23.4; tr. J. Gavorse]

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