I know the Spanish went through a civil war. I know Gibraltar is a fortress. Yet, when there are threads like this, most are crushed by a reminder of Gibraltar's cavelike labyrinthine tunnels. Fighting through those would be nightmarish. But I had an idea that might allow this. What if the Germans and Spanish, once securing the exterior (which is the "easy" part) sealed the exits and flooded the tunnels, either with regular old water or with poison gas. Even Brits need air, right?
Thoughts?