The spectrum isn't just even-matched or roflstomp. There's lots of room inbetween.
True, no sane general would give up superior numbers for a bit of prestige. However, no sane general would set an army in motion to stomp a single unit.
Somewhere in there, we can find happiness. A not-quite-even battle is also fun, because with proper strategy and a bit of luck you just might be able to win it.
We could improve some retreat code or something to allow people to withdraw from battles they have no chance of winning.