How do I get my ratizens to fight? I dug down, found an enemy... and the enemy sent an army into my base. The tutorial was just telling me how to fight them all by myself, but I couldn't win that way.
I assume that if the entire city (or maybe just half the city) had mobilized against the invaders, we would have won, but the ratizens didn't do that automatically and I couldn't find a button for it.