Quote Originally Posted by Simetrical
How? TNT?
Nope, reread my post. The spy is an agent. He doesn't do the handiwork himself...he finds others to do it. But don't take my word for it, read about the Punic Wars, etc. and form an opinion. Quite a few cities changed hands through various forms of treachery. I can find no reason to expect a "successful" gate opening would leave the gate tower defended. Typically the guards at the gate were either murdered or part of the treachery. Either way, the gate defenses will not be operable at the start.