Circa 12 B.C. Augustus made a further decision to move the western German border from the Rhine to the Elbe. He was uncomfortable with the gap in the Black Forest that separated the sources of the Rhine and Danube and realized that moving the western border to the east, he could eliminate that gap. The eastern advance was entrusted to Drusus who began his campaign in 11 B.C. By the end of the year he was successful in working his way to the Weser River.
In 9 B.C. Drusus moved all the way to the Elbe before his unfortunate death in a riding accident.