Mid/late game defense against undead??

[sfsuphysics]

So I'm playing my latest game, on a small map (60ish territories including water), and essentially own the west coast of the continent with a nice well defended border and left the coast virtual undefended (no water races only the neutrals) and 1 tough neutral with a hundred or so heavy cavarly figured I'd just leave him there since my attack/defense force was thinning out some and it makes a good enough defense just leaving it there (mistake #1).

The very southern tipe is a C'tis owned areas, so I leave a demon commander and a high inquisitor, enough to stave off any attacks from the lizzies.

To the east is the python guys their god's city is right ont he border to I put the majority of my forces in there Druid (6/5 nat/earth) Archdevil(10 Fire and my prophet), Devil(7 Fire) and a King Elemental (5/3 Earth/blood) , not many troops, about 20 clockworks, some imps that survied earlier battles, a few mechanical men and 100 defense in the province (yah you got it, flame arrow ,and WOOF enemy dead). Unfortunately the pythons got a hill fortress, and with not many troops attacking that place would be silly, so I wait it out making more troops magically (I have a buttload of gems/slaves), then I notice Ermor attacking.. sweet.. he's got a huge box its about 200 troops, couple turns later boom the Pythons are no more god is dead.

Unfortunately a few turns after that the box turns absolutely huge so that its larger than the land, a click over at the army and they have close to 1000 troops! Granted they're the weaker(longdead,etc) ones but without a need for supplies NOR upkeep this guy is a definate threat.

So before I know it that neutral province I used for defense falls and I only know this because it takes one of my hardly defended territories right behind it (mistake that bit me in the butt!). Now they're attacking my main city with my God! Now I choose the blood fountain god so I can't move (maybe this is a mistake), luckily I have a lot of magic at my disposal (12 blood, 2/3 in about every other magic) so I can summon like mother, did a couple level 8 blood summons (Demogroras??), unfortunately the only other defense there was 5 mages (who were researching, and not very powerful in any magic) and a def of 30 in that province, needless to say that the defenders fell instantly.

I still figure I had it under control (forgot I had a mage tower so my defense if they breech the walls, which they did, isn't very tough) luckily my 30ish troops had enough high level magic to take out 200 undead, after a few turns I feel its wise to bring maybe that druid and archdevil back to help get things under control, and in a few turns they were within striking distance. Now after a while and summoning all for of those Demogra..etc I broke through the seige, wiped out about 600 undead (plus 12 leaders) and took back all my territories.

So I click on a good hunk of my attack force (archdevil,druid, demons, Vampire Lord, etc) and go attack the one place that busted through to breach my defenses. Next turn, nothing, none of my troops moved EXCEPT the sneaking one (vampires), now what the hell is up with this? Fine did it again, still nothing *grumble* must be a bug here. So I had to go to another territory then click to it and I wiped him out (and before anyone asks YES the original terrority was right next to it). So I take him out, he's dead..

Unfortunately he launched an attack at my base again the same turn I moved into his terrority, so he again broke through the defenses, now I took my attack force back to the base (which they were able to get to now) but then he left the seige and went to attack some other poorly defended areas I just won back.

On top of everything he took over the underwater provinces, since undead apparently dont need to breath this isn't a problem for him, but it is for me since now I have very little money (the many turns of seiging hurt bad) and poorly defended coast line.

So after that huge tragic story to which I'm curious who actually read, I'm left with this delema, how do I fight off this onslaught of constant troops that he can just summon at will. I'm sure he probably owns most the rest of the continent, and the water, probably has a bunch of priests and whatnot that are constantly raising the dead, so within any given turn he can reenforce just about any one of his cities with a couple hundred troops.

I'd hate to see how games play out on bigger maps (200+ territories) where the computer DEFINATELY has the advantage due to the ability to micromanage more quickly.