First shot fired?

[zapat 56]

I have a dynamic battle setup. 50 men on west side, 50 men on east. One side is closing on the other probably in combat mode.

Does anyone know a lightweight method to determine when the battle is starting: that is when the first shot is fired? Without the need to know who fired at what (disregarding player). Or any other idea on how to check if any units are in fighting distance?

I can only think of brute force checks but I'd avoid those if possible.

Thanks

[The Hebrew Hammer 10]

try the "fired" eventhandler