Wrong indication of Army

After putting together a full (200 head) army, and attacking a village in a new sector. The village is indicated when cursor is placed over it, as easy, with 80 heads.

For the first time in the game, I lost all soldiers, and the general had to recover for some time.
Unfortunately, I never looked through the battle report.

So I put together a new army, again with 200, and with cavalry etc, which should be enough for an easy level village.

Again, I lost all soldiers.

When looking through the battle report, the numbers of soldiers in the village, 180 was higher than indicated 80, and there was a surprise of 120 wolfes.

Is ths a bug?

It's not a bug. You got intercepted. The mail you got should say you got intercepted as well, i think in the subject.
There is already a patch on the test server that makes it clearer if you will get intercepted before sending your general.

I got the same problem as Coel. I replayed the battle report and there is no mention of an interception. But Dible's explanation makes sense considering that the attack was by rangers and guard dogs. Now how do you get around that?