the Reichspost and deployed around Leuna. Two detector systems were ordered: a simple passive system that was essentially just a high-frequency receiver, which became Naxos, and a much more sensitive system using its own magnetron as a local oscillator known as Korfu. Both required crystal detectors in their receivers, and a crash program to develop them began. These began delivery in a few months, but proved difficult to mass-produce and extremely fragile in the field. This limited the availability of the Funkgerät (FuG) 350 Naxos radar detector to a handful of operational examples, which enabled Luftwaffe night fighters to home on the transmissions of H2S. A U version of the same equipment was used to allow U-boats to detect microwave-frequency ASVs. The RAF remained unaware of the Naxos until the spring of 1944 when a number of intelligence reports suggested the Germans had developed an H2S detector. By this time, the Germans had only a few dozen such detectors in service, but the reports reopened the longstanding debate between the supporters of H2S and those of UK-based navigation systems like Oboe. This corresponded with a period of increased losses among Bomber Command, and there were calls for the system to be abandoned. The matter was debated for months. The issue was finally settled by a study by Saward. He noted that losses during the Naxos period were actually lower, down from 4% to 2% of the sorties. The drop corresponded with the introduction of Fishpond. Saward concluded that: In July 1944, a Ju 88G-1 of 7 Staffel/NJG 2 flew the wrong way on a landing beacon and landed at RAF Woodbridge by accident. The crew were arrested before they could destroy their equipment, providing the British researchers with the latest version of the Lichtenstein SN-2 VHF-band radar, the Flensburg radar detector, and the FuG 25a Erstling IFF gear. Interrogation of the crew revealed that the Flensburg system detected the RAF bombers' Monica radar emissions and that it was used as a homing system. Naxos was not fitted, and the crew stated that it was only used for initial warning, not as a homing system. This was all to the great relief of everyone involved; Monica was already being replaced by Fishpond systems on most aircraft, and those aircraft with Monica were told to turn it off. H2S remained in use for the rest of the war. As the British engineers