led by accurate marking in Karlsruhe, and the raid was considered a great success, with an estimated 200 fires seen burning. Reconnaissance photographs showed much residential and some industrial damage. A very short report from Karlsruhe says only that 73 people were killed and that three public buildings in the city centre were hit. Improved technique As the PFF gained experience, new problems appeared. Many bombers in the Main Force lost their way to the target and either bombed randomly or turned for home. Another problem was that the illuminators would go out before the raid was complete, leaving the following aircraft to bomb on visible fires, if there were any. This led to the problem of "creepback", when the newly arriving bombers would drop their bombs on the near side of the fire so they could turn for home earlier. This led to subsequent bombs slowly walking backward along the attack vector, away from the target. To address these problems the PFF adopted new techniques. Their force was split into three groups for each raid. The "illuminators" would drop white target illuminators at points along the attack vector, allowing aircraft to follow these markers over long distances and thus avoid getting lost en route. The "visual markers" would drop coloured target indicators on the target, but only if they were sure it had been identified. Finally the "backers-up" or "fire starters" used the visual markers' flares as the aim point for their own incendiary bombs to light fires in the proper location, which would burn longer than the flares. The new technique was first employed on 4/5 September 1942 on a raid of 251 aircraft against Bremen. The weather was clear and the PFF marked the target correctly, with the majority of the following Main Force finding the target and bombing it. The post-raid analysis showed that 460 houses had been destroyed, 1,361 seriously damaged, and 7,592 lightly damaged. Added to this list were hundreds of light and medium industrial buildings, including the Weser aircraft works and the Atlas shipyard and associated warehouses. The raid was a complete success. Another improvement was the introduction of larger bomb casings for the target indicators, starting with the "Pink Pansy" in an adapted 4,000 lb casing. Using these for the first time on the night of 10/11 September 479 aircraft attacked Düsseldorf and caused enormous damage. In addition to thousands of houses