Monsieur Alphonse, I think you might be putting all your eggs in one basket there....don't want the elephants to see all our clever tactics at once.

After all, they never forget, and I'm quite sure they talk...

On the topic of using siege weapons on the battlefield, what about using RTW sappers against the passive AI?

Imagine them all standing at the bottom of their hill or wherever they've decided to hang out determinedly ignoring your missile fire, and suddenly all falling into pits

or you could mine under the spearwall, come up the other side and kill the general...