Help w/ Battle of Vittorio Venetto Dual Monarchies

I managed to breeze thru most of this campaign but this last campaign seems nearly impossible. You must defend for 24 rounds against a complete onslaught of Italian, then French, then British troops. I have Hotzendorff, Moltke, and all the free generals from previous campaigns, but they still get so worn down over time there it doesn't matter. I have tried attacking the Italians a bit in the south at first, but then get overwhelmed despite doing OK against their generals. My allies in the north and south seem to collapse after round 10 which is where I began to struggle. Any help appreciated.