This is my first attempt at making a Stronghold Invasion map, completed with some help from users at stonghold heaven and in particular Duke Chris who suggested I upload it here. If you see something glaringly bad or wrong about it let me know and I'll try to fix it. I may or may not make any additional maps as RL and time allow.
You will have a good long time to prepare for your first invasion (possibly too long, but I was erring on the side of not allowing enough time to build up in previous versions of this map), but following that first one, you will undergo wave after wave of progressively larger and more serious invasions (multiple AI which I attempted to orchestrate for synchronous attack). Victory is achieved if you make it to 1066 (start date is 857 if memory serves) and there are not invasions of enemies left. Repeating invasions _should_ switch off at end of year 1064, so if you've killed all enemies by then it is a simple matter of fast forwarding to victory.
I have only playtested it to about 908 AD, but it seems to run smooth up to that point, and is definitely 'doable' at least up to that point.