Along the same lines:
Remove your defenders from a city,and park them just outside. The AI will recognize that the city is weakly defended and send some troops in that direction. When they start to get close, put the defenders back in the city, and remove them from a city at the opposite end of your empire. The AI troops will turn around and make their way to the newly "defenceless" city. A pre-1.29f exploit, don't know how it will work these days.