So... why would I want to build any dragoons or keep building them to upgrade them outside of some UU promotion? I can't think of any reason I would really. If the problem is I'm out of oil, there's ways around that (CS, conquest, expansion, deleting inexperienced BBs), but the solution isn't usually going to be "I will build a large horse-drawn army" instead of "I will build lots of destroyers, infantry, artillery, or air units".