Animal studies show that external-beam radiation therapy (RT) radiotherapy is more effective when delivered at very high dose rates, a process called FLASH. We propose the development of a dose delivery system satisfying the extreme performance requirements of FLASH, and ready for clinical application. Phase I investigated detectors and electronics of interest to research and commercial leaders in the field. Phase II will develop the prototype technology demonstrated in Phase 1 into a clinically capable dose delivery components and systems. The technology will satisfy the need for dose control, beam position control, and safety interlocking, all of which have challenges specific to FLASH. Although we will concentrate on the most challenging delivery mode (scanned proton beams), we will accommodate the promising options of pulsed electron and photon beams as well. Optimized planar ion chambers, support electronics, and diagnostic devices tested in Phase I will be completed and submitted for testing. The development of clinical architecture will be supported through our continuing collaboration with clinical research partners, plus outreach to established commercial developers. The system will meet the clinical requirements of speed and safety, including innovative technology capable of making safety decisions and system response on the microsecond time scale.