1 day gig, about 60 participants in total. Lord of the Rings related battle game, depicting the battle on the Fields of Celebrant.
The game also had two distinctive features - first time we got proper artillery - namely a small balistae and headcam footage.
Anyway, few tips I can give, based on my experience.
1 - always have backups for important roles. The great khan of the easterlings disappeared without warning. That gave me quite the problems.
2- Don't expect people to read up on what they are supposed to do. You will have to explain the same stuff 3-4 times. Its best to have some printed lore lists for the job.
3- Have plan C for logistics just in case.
4- Actual terrain preparation involving proper wooden barricades is not so hard - especially if you are in a forest and finding fallen trees is easy. Its much better than "pretend its a stone wall fishing cord".
Somehow the game went well. Could be better of course. Definitely got some experience for later.