I fried the last few with fireballs, I checked that all were dead, however the block kept running away off the screen. My units followed...off the cliff as well. The last unit was a little smarter and did not follow.
After another 30 seconds the battle finished.
I won, this time. I saw another similar one where it was a draw.
It would be nice that when you kill the last soldier on the other side, battle stops then, not when most of the blocks have left the field. If the survivors want to loot the field, fine. I would rather not watch.

I would also think if you kill the other side, you should at least get some rewards. These were a small town rebel uprising. No loot. Cheap peasants!