Science fiction promised us force fields. Epirus built one and put it on a trailer. Leonidas is a high-power microwave system that does what no gun or missile can. Rather than engaging one target at a time, it floods a volume of airspace with directed electromagnetic energy. Anything with unshielded electronics that flies into it stops flying. In a Department of Defense demonstration it neutralised 61 drones out of 61 across five flight scenarios. The physics is elegant. Every conductive trace on a circuit board is an unintentional antenna. Wiring harnesses, motor leads and controller traces all absorb radio frequency energy and convert it into induced current. Push enough field strength across that structure and the induced voltage exceeds what the silicon can survive. Gates break down. Junctions latch up. The autopilot stops computing. Engineers call the two attack paths front door and back door coupling: - Front door: energy enters through the intended antenna and overwhelms the...