Please don't kill me for being a newbie at scenario designing, but I'm 99.9% sure this will solve your problem without your having to use custom AI. (I've used it a good bit so far in my Robin Hood scenario.)
Let's say Player 1 is the procession, and Player 2 is the archer:
ChangeDiplomacy:
Condition 0 - Object in Area(P1 Longboat, Area=Right after the procession starts)
Effect 0 - Change P2-P1 dip. to enemy
Effect 1 - Change P1-P2 dip. to enemy
If you wish, you could display a blank instruction to get rid of the "P2 changed diplomatic stance with you to enemy" message.
An alternate way to do this would be to change the diplomacies when you start the longboat moving.
BoatStandStill:
Condition 0 - Own Object (P1, Longboat)
Effect 0 - Freeze Object (P1, Longboat)
This is initially disabled, and is set to loop.
DestroyBoat:
Condition 0 - Object in Area (P1 Longboat, Area=Where the boat gets destroyed)
Effect 0 - Activate Trigger (BoatStandStill)
Effect 1 - Task Object (Make the archer fire at the boat)
This freezes the boat, and sets the archer firing. Since you're using the freeze unit command, the boat won't run and/or fire back.
In case you don't understand any of this, I'll try to have a little example done by Monday, and post it to my website.
My website is
http://homestead.juno.com/majm101/index.html ------------------
The Khan
E-mail: majm101@yahoo.com
ICQ# 72893056
ICQ ID: WacoMitch
AOL IM ID: WacoMitch