Hell Birdy. It could very well be true. It was a big production. When shooting a close up they could have used it as they would simply just prime the pan for effect. Need lot o' sparks!
When we were out on the battlefield it would not have mattered. Just lots of smoke anyway. No close up stuff.
I also remember the day all the Reenactors came close to walking off the set. In the middle of the big battle finale. Another story for another time