Isn't the retreating unit automatically the loser of the combat? You could simply check if the losing unit is still alive, if I'm not mistaken.
mmhh....how are siege units handled there?
i was wondering, is it possible to make fish (or a certain type of fish) to appear only on lakes?
mmhh...not by XML.
Theoretically you could have an additional function run after the game start which "manually" places fish in some lakes.