Here's an Amtgard SKBC video regarding some small-unit tactics. It's got some good information there, especially when they talk about their planning and how it can change very quickly.
http://video.google.com/videoplay?docid=-6010909567955457306
P.S. The video is 16 minutes long. Stick around after the credits...
P.P.S. If anyone is interested the SKBC (Sword Knight Boot Camp) is tentatively scheduled to be held in Cedar Rapids, IA in 2007. I'm not sure if the dates will conflict with Spring War, but if you look at the course notes, it's definitely worth checking out.