Another thought on unicorns, would be to assume they're small enough to 'meld' with an army, but are glass cannons. So, they can blockade from a zone away, but without orders to defend, they aren't numerous enough to stop an army from passing through, and if an opposing army declares an attack against them it succeeds without support, though in that case both armies are obliterated in the clash.
This would allow anti-squadron support with a 'defend against all' order
We'd need rules too, for squadrons setting up camp in a zone that has a not-expressly allied army below. If no order to the contrary is given, do we assume they try to peacefully co-exist, or that opposing armies by default will pester each other, causing movement rebuff?
For fun, you could declare a map, or a year, to be 'cloudless' -- that would mean that while squadrons could pass over opposing armies, they couldn't stop for the night there because they couldn't keep the clouds around long enough to put up their tents -- all occupation MUST be on the ground at the cessation of movement.
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