Zombie Rising from the Grave

I've never really understood the re-enactment thing (although I love scenario paintball, even if it usually doesnt follow a textbook battle). How do you know when to be shot? Is it one big argument of "Gotcha gotcha!" and "Ting! I'm invincible!"? What's to stop someone from breaking script and bayonetting an important figure, thusly changing the outcome of history? Where did I put my damn car keys?

By the way, nice pics. Is it just me, or are the brave union troops a bit on the pudgy side?