The SCR-268 (for Signal Corps Radio no. 268) was the US Army's first radar system. It was developed to provide accurate aiming information and used in gun laying systems and directing searchlights against aircraft. The system was already considered out of date by the end of World War II, having been replaced by the much smaller and more accurate SCR-584 microwave-based system after the Tizard Mission provided the US with the cavity magnetron.