firstly, thanks again to Google Translator.

check the ideas e.g. in "Empire Earth 2", "Cossacks" and "Rise of Nations", the military system of "Rise and Fall" and the "Total War" series.

you can add things like: occupy areas, build there separate towns instead of those long walls, make scientific developments, and improve your civilisation from stone age to modern ages until the final undefendable ufo attack from the space... I could write pages.