an experimental set was first used over Berlin on the night of 18/19 November 1943. In comparison to the first mission with the Mk. I sets, the results using Mk. III were described as "most outstanding". Mk. III was rushed into production and saw its first real operational use on 2 December. From this point until the end of the war, the Mk. III became the backbone of the Bomber Command fleet, and a large variety of versions were introduced. The first modification was the out-of-sequence Mk. IIIB, which added the range corrected Type 184 display unit from the IIC models, but lacked roll stabilization. Stabilization was added in the next version to see service, the Mk. IIIA. The new "whirligig" scanner was added to the Mk. IIIA to produce Mk. IIIC, while the original scanner with a higher power magnetron produced the Mk. IIID. The Type 216 display, using magnetic deflection, which was much easier to mass-produce, was added to the original IIIA to produce the Mk. IIIE, while the whirligig was added to the same unit to make the Mk. IIIF. By the middle of 1944, the war in Europe was clearly entering its final stages, and the RAF began making plans to begin attacks on Japan with the Tiger Force group. In order to equip these aircraft, which would need both targeting and long-range navigation, a conversion system for the earlier Mk. II units was introduced. Based on non-stabilized IIC units, the Mk. IIIG used a new magnetron and receiver for 3 cm operation like the other Mk. III systems. The primary goal was to use it for long-range navigation, as opposed to bomb aiming. The final Mk. IIIH was IIIG with the Type 216 display. Rotterdam Gerät 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, one of the Stirlings carrying H2S was shot down near Rotterdam by the crew of Oblt Frank & Fw Gotter. The device immediately attracted the attention of Wolfgang Martini's technicians, who managed to salvage everything except for the PPI display. Giving it the name Rotterdam Gerät (Rotterdam apparatus), a group formed to exploit the device and met