In the more likely case the Soviet and Hungarian divisions would invade Austria and march through Southern Styria and through the Drava valley in Carinthia the alpine brigades would have been the first front line units of the Italian Army. The Julia would have defended the Canal valley, the Cadore the Piave valley, and the Tridentina the Puster valley, while the Taurinense would remain in reserve. Officially the Orobica, with its two Alpini battalions and two Mountain Artillery groups, was tasked with defending the vital Reschen and Brenner passes. However, the true mission of the Orobica was to advance into neutral Austria and link up with the German 23rd Gebirgsjäger Brigade of NATO's Central Army Group in Southern Germany. It was considered vital to establish a line of communication between the Italian Army and the allied armies fighting in Germany. Therefore, the Alpini Battalion Morbegno and the Mountain Artillery Group Sondrio based in Sterzing would have advanced over the Brenner Pass and through the Wipp valley until Innsbruck, where they would have linked up with German and American forces coming from Mittenwald and through the lower Inn valley, while the Alpini Battalion Tirano in Mals supported by the Mountain Artillery Group Bergamo in Schlanders would have crossed the Reschen pass and advanced until Landeck, where they would have linked up with German units coming over the Fern pass. Although Austrian military defence plans envisioned a strong defence around Innsbruck to deny an invading force the use of the many important roads crossing the city, there was a tacit understanding that NATO forces would not be opposed if Warsaw Pact forces had invaded Austria first.