They look like a larger version of the European Hornet. I've had plenty of experience with the European Hornets. Those are supposed to be non-aggressive unless you disturb their nest. Well, the only time I encounter them is when I disturb the nest. I've encountered nests in logs and underground. You have to watch out what you try to collect for firewood and where you step.
Once you have upset them, it's time to run. They are mean, like a larger version of the Yellow Jacket (which is another colony-living wasp).
If my experience with the European Hornet is any measure, dealing with a angry swarm of hornets that are twice as large must be painful.
Not to mention the occasional wolf spider you find in a pile of wood, y'know, the kind that grows to about the circumference of a small coffee saucer. Forget hornets, a spider that
size is enough to cause cardiac arrest just be looking at it! ( I speak from experience.)