A simple tip when going for a city....take along 3 or 4 engineers in your raiding party....then when your holed up outside the city limits get them to build a fortress. It seems to increase your attack effectiveness (maybe by increasing defense?), your less likely to take damage if counter attacked from the city, and you also get a free pop at any military units that move outside the city and are within range(if you have the right units).
simple but effective.
simple but effective.
