It'd been called 'combat training', although it was more a show of strength, since it only required they watch.
"You could stop them - the bullets and shells. Isn't peace is a worthy goal?"
"Even you're not that naive, Charles. There would simply be chemical warfare, plagues, or even trebuchets and flint arrows. You can't stop man fighting: it's his nature. You can't have both a free humanity and a peaceful one."
"But co-existence is becoming a matter of self-preservation - you must credit them with some intelligence."
"They will only unite against us, my friend, you know that really."