In the second-to-last picture you might work out one of our tactical blunders. The right thing to do in this situation would be to have at least two of us stand at the door, blocking his escape. What happened instead was that we all blurted towards him, allowing Akrabu to circle around and run out of the cave.
It's interesting to imagine what a large war would look like in this game. Whether it would consist of a disorganised rabble huddling together, or if some groups will be disciplined enough to be assigned to blocking parts of the battlefield, even if they're being tempted by a routing army dropping items everywhere.