I stand corrected. Even in an Entrenched country, the enemy doesn't start with a Battle Forge already built, they just start building one right away, and then a second one immediately afterwards. That doesn't seem like a terribly winning strategy to me. It takes them far too long to start producing armoured units.
Bug:
I saw a graphical glitch when targeting Mustard gas on one map ( I can't remember it's name but it was something to do with death). The next map, I tried targeting with that skill and didn't see the glitch.