 Starting in 14 BC, Drusus built a string of military bases along the Rhine—fifty according to Florus—and established an alliance with the Batavi in preparation for military action in Germania Libera.He is likely to have had seven legions under his command.In spring of 12 BC, he embarked an expeditionary force, perhaps consisting of the Legiones I Germanica and V Alaudae, by ship from the vicinity of modern Nijmegen, making use of one or more canals he had built for the purpose.