This is very simple. Press the "esc" key and go
to world builder on any level you are on. You'll
have two boxes, the one on the top left corner
has all units, buildinds and technologies. I
suggest you put 3 navy seals next to ever enemy
city. Or put ICBMS in your capital and launch
them everywhere. You can also delete any unit
from the map by right clicking on them. And when
you exit, everything done will still be the same.
Conquere the world in one turn/year. Napoleon
could never do that.