AI Crusade defeated by 'duff' default map.

I've been tinkering with a DIY mod recently and got a bit carried away with playing the campaign (as the Almos) when I should have just let it auto-run for testing purposes.

Anyway, a large crusade force sweeps down to hit me in Cordoba and I muster as much as I can to meet it. I'm not hugely outnumbered but both their numbers and quality, relative to my troops, show that it should be quite a testing affair.

I see off the first wave (unexpectedly weak troop mix, except for some knights) and manage to stop my men from pursuing routers. I sit and watch the first lot leave. I wait....and I wait...the clock ticks on and an eerie silence pervades the field. What the heck is going on?

I half-forgot that I'm running with the -ian switch and this gives the camera total freedom of movement. While panning as far forward as it can go, I stumble across the fact that it doesn't 'hit the buffers'. It carries on going and I eventually find myself at the far edge of the map. Peasant units are already there and they were supposed to be on 'page 3' of the crusade, so it has already cylced through its entire second wave without any of them reaching the fight. I soon work out why.

Basically, the edge of the map has a long, but narrow, strip of level land, only about 3 or 4 unit ranks deep. The units are then faced with a 45+deg upward slope, to a hilltop maybe 50-80 times as tall as the men appear (i.e. more than 300' high) before a downslope to the central plain and I'm on an upslope at the other end.

Their units barely have room to 'form up' before proper marching begins and they simply cannot climb this steep slope. UNits are busy withdrawing back through incoming units and everything is very crowded down in this narrow gully. One or two units are about halfway up the slope at the point the game decides they've withdrawn the last of their units and lost the battle (not a time limit thing, yet) but I think these just arrived at a sweet spot but were struggling as the incline steepened. None of the slope was marked in grey as 'impassable' terrain, by the way.

I've long since noticed a lot of maps have very steep run-offs at the edges but this is the first time I've seen it have such a dramatic effect on a battle result (I was ultimately relieved it made things go in my favour, as Cordoba's income was twice my annual cashflow and loss of it would have brought my 'testing session' to a premature end but, all the same, I previously had hopes of really good punch-up to justify such a win).

This edge effect helps explain why some battles take an extra minute or two to properly come to an end after you've lost sight of the last of the enemy and it also explains why your own reinforcements sometimes seem to take an age to arrive and are already half-knackered by the time they reach the assembly point flag. It's even worse in the desert, though perhaps the heights and slopes aren't entirely unrealistic for those truly monumental dunes, in that part of the world.

This post was partly inspired by the map-editor thread. I've not been tempted to tamper with any of the default maps so far but this problem shows that there is much scope for modders to do more than just introduce new units and factions.

I have mappack3 (custom multiplayer maps) and that was a quite-reasonably sized download, considering the number of maps it contained (50 plus??). Unfortunately, there is no way to pursuade the game to include these in the random selection it makes. The filenames seem to be important to the selection process, so you can't have an expanded set to choose from, you will have to overwrite the default ones with replacements, renamed to match them, to actually see them being used.

Your own observations of this phenomonon would be most welcome.
(I'm familiar with the problem of AI units getting stuck while attempting to withdraw, which is related to duff maps but not what this is about).