Plans for the revenge were started by the Emperor Augustus, and put into effect by his successor Tiberius. Germanicus had command of eight legions, one-third of the Roman Army. He destroyed the opposing German tribes, and recovered two of the three symbolic legionary eagles which had been lost. He was called back by Tiberius after he crossed the Rhine. The reasons for the recall are not agreed, but Augustus had set the Rhine as the limit of Rome's ambitions in Germany.