 John finally reaches the Crusades. And he's about 21 years old now. It's the summer of 1601. It doesn't take long before he makes a name for himself. So in this battle, they're outside a walled city. And at that time, their guns were called matchlock muskets. And the matchlock musket always had a small fuse that stayed lit. So at dark, you could see a little glowing ember. So John went to the leader of the regiment and said, I have this idea.