I heard a whoosh! as one of the rebels fired a rocket. But then came the dull clunk of the rocket striking stone—without exploding. The rebel might as well have saved the effort. A rocket’s smart circuits are designed to prevent it from exploding unless it has traveled a minimum distance from the launcher—typically twenty meters. The tlachtli that formed the sub-basement of the church and convent was simply too short—or too cluttered with rubble—to allow the rocket to travel that far. Our most powerful weapon was useless.