Playing as CSA in early August 1861, I'm trying to build a depot in Winchester, VA, but the game won't let me do it. I have Shenendoah army there (with its supply unit) as well as an independent supply unit, but the Build Depot button is grayed out for both.
What's more, the button (which shows a hammer and a little structure) gives me a tooltip about why I can't "raze the city" instead of anything about a depot.
Any thoughts?