Before H2S was deployed in 1943, there was an intense debate over whether to use it due to the possibility of it being lost to the Germans. As it turned out, this occurred almost immediately. On its second combat mission, during the raid on Cologne on the night of 2/3 February 1943, shortly after crossing the coast one of the Stirlings carrying H2S was shot down near Rotterdam by Reinhold Knacke. The device immediately attracted the attention of Wolfgang Martini's technicians, who managed to salvage everything except for the PPI display.