On its second operational mission on 2/3 February 1943, an H2S was captured almost intact by German forces, and a second unit a week later. Combined with intelligence gathered from the surviving crew, they learned it was a mapping system and were able to determine its method of operation. When they pieced one together from parts and saw the display of Berlin, near panic broke out in the Luftwaffe. This led to the introduction of the FuG 350 Naxos radar detector in late 1943, which enabled Luftwaffe night fighters to home on the transmissions of H2S. The British learned of Naxos and a great debate ensued over the use of H2S. Later calculations showed that losses after the introduction of Naxos were actually less than before it, and use continued.
