Thanks! Yes, it's taken me years to get even vaguely confident with Gimp. I got it originally for making icons, and spent the initial four months opening it up, staring at it in despair for a while and then shutting it down and going away again.

There are a few stock photos of reenactors available - not a great selection and not with any visible faces. But you can usually find photos of equipment and architecture, and sometimes even original art from the era. That can be better than photos, because a painting gives some gravitas.