Very hard campaign vs population

The A.I. gets more money to spend wich means more troops wich means less of a population wich allows a quicker steamroller effect. All I had to was defeat there first 2 armies and go city to city smashing them. I hit 20 in a row with no population wich made me quit because I realized they bled themselves dry befor the war even began.

If you make the cities large enough and a few other adjustments you can get around this. One thing I am noticing though...if I don't put a simple wall on the strat map for the AI cities as well, it seems reluctant to build one.