destroyed or heavily damaged, 39 industrial firms in Düsseldorf and 13 in Neuss were damaged so much that all production ceased, and 19,427 people were "bombed out". German counterefforts The Germans were well aware of the RAF's target marking, and quickly deduced the basic strategy was a copy of their own from 1940/41. German intelligence reports from later in the war show a wealth of information on the PFF. On the night of 15/16 October 1942 on a raid by 289 aircraft against Cologne, the Germans lit a decoy target indicator that deceived the majority of the Main Force's bombs. Only one 4,000 lb, three smaller General Purpose, and 210 incendiary bombs hit the city, of a force of almost 70,000 bombs in total. Follow-up efforts during October and November were mostly small raids, including a number against cities in Italy. Weather and operational problems meant that raids during this period were limited and of greatly varied results. New systems, increasing tempo On 20/21 December 1942, H. E. Bufton personally led a force of six de Havilland Mosquitos on a raid against a power station at Lutterade, a small town in the Netherlands. Led entirely by the new Oboe navigation system, several bombs fell within 2 km of the target. The test was considered a success. A follow-up under more realistic conditions was carried out on the night of 31 December 1942/1 January 1943 against Düsseldorf, with two Mosquitos leading a force of eight Lancasters. Only one of the Oboes worked, but that was enough for the following heavies to bomb on and hit a number of industrial buildings. Another mission by three Mosquitos attacked the German night-fighter control room at Florennes airfield in Belgium, but there was complete cloud cover and the results were not known. It was clear by this point, after less than six months, that the PFF concept was a great advance. Picked crews from the bomber groups were allowed to transfer and the PFF soon expanded into a completely new Group—designated No. 8 Group (PFF)—in January 1943. In April 1943 the group's strength was increased by two squadrons, with No. 405 (RCAF) Squadron, flying Halifaxes and No. 97 Squadron, flying Lancasters. In June the Pathfinders gained two more squadrons—Nos. 105 and 139 Squadrons—both of which were flying Mosquitos from RAF Marham. Later in the month Pathfinder HQ moved from RAF Wyton to Castle Hill House