Well i'll tell you how many i lost to the relief army.

0. none. no one. Why? because my entire army got wiped out by the garrison.
The end stats were something like "enemy killed 87,enemy kills794"

btw i been playing MTW for a few months. Never have i had such a defeat . But then i only win under these conditions "MY army elite units/number/valour/general's command all> than enemy elite units/number/valour/general's command" thank goodness for my civ3 strategies or i'll have no chance.