It was the huge cost in men and aircraft of the Berlin campaign, which ran over the winter of 1943-44, that first caused Harris to rethink the policy of large-scale unified attacks against the German cities. There was also the pressing factor of the forthcoming invasion of Europe, which would need maximum support and therefore necessitated cutting down on the enormous wastage of bomber crews.
Harris began to consider the possibility of better results being achieved by smaller and more easily controlled attacks, in particular those being pioneered by 5 Group, led by Ralph Cochrane. Cochrane had been a flight commander in a squadron commanded by Harris in Mesopotamia in the 1920s and was a very strong supporter of Harris. In addition, Harris probably found him easier to deal with than Bennett.
5 Group had an almost magical status because of Guy Gibson and the Dam Busters of 617 Squadron. 617 Squadron was now led by Leonard Cheshire. Cheshire was convinced of the superiority of low-level target marking and demonstrated this to spectacular effect in an attack at Limoges filmed by the RAF Film Production Unit. Cochrane was so impressed by this particular raid that he went to Harris to propose low-level marking techniques be used on Berlin.
However, when Harris spoke to Bennett about this idea on the telephone, Bennett rejected it. He conceded that these tactics might be useful in some circumstances but not when flying over densely built-up areas at night. The conversation ended abruptly, and with no warning Harris suddenly set in motion the transfer of 83 and 97 Squadron to 5 Group, together with the Mosquitoes of 627 Squadron. It was a massive personal blow to Bennett, and one which shook the morale of the Pathfinders.
However, the PFF retained C Flight of 97 Squadron, which in March 1944 moved to Downham Market to become part of the newly formed 635 Squadron.