Medal - "Fight without losses"

[Phyrex]

I'm about to start with KB's AP and have a question about the new medal system.

The Grand Strategy medal talks about "fights without losses", does that mean not a single cassualty on the battle map or does it mean not a loss of a complete stack of units?

Also, if you resurrect a fallen unit/stack, does it still count as a loss?

And last; do the no loss battles need to be in succesion of eachother or can you 'fail' a battle midway and still get the medal without having to redo a lot of battles?

Thanks.