I've owned this game for something close to a year now and I finally won a grand campaign! I should really say "I finally get the logistics/supply!" because that's why I won. I was able to keep my Austrian armies supplied while avoiding battle and repeatedly trapping Prussian armies in bad supply areas or forcing them to winter in bad supply areas (Twice luring armies to their doom near Prag and 3 times trapping armies in the Bohemian/Silesian Mountains in the winter), then pouncing on the weakened Prussians, wrapping things up in August 1759 with the fall of Magdberg.
I love that you can pursue an effective logistical strategy. It's very authentic feeling!