The concept and the somewhat contentious creation of the RAF Pathfinder Force (PFF) through 1941–42 has been well documented. There was considerable difference of opinion between major personalities about the need for; the possible manner of conducting what was initially named as Target Finding Force (TFF) operations; and the potential effect on morale of the bomber aircrews at large. In many respects, the proposed creation of a TFF would have mirrored the Luftwaffe and the KG 100 specialist unit that operated over the UK using the Knickebein beams, transmitted from fixed ground stations in Germany and France. The reader’s attention is drawn to the earlier comments, within the description of GEE, about that episode.
It is a matter of recorded history that the CinC Bomber Command was not convinced about the initial proposition and did indeed resist the formation of the TFF, later to become the PFF. The CinC favoured the use of the best squadron crews to lead the attacks by squadron and later, when cameras became available to record bombing results, that the best squadrons be selected as Lead Squadrons for the Main Force during the following months. At that point in time the Command did not have any operationally tested and proven radar navigation aids. GEE was in the process of introduction into service and the early experiences were mixed; this has been briefly portrayed in the Air Navigation section above. The policy arguments between the CinC, the CAS and Gp Capt. Bufton (initially Deputy Director and then as Air Cdre, Director of Bomber Operations) about the TFF and PFF may possibly have sown some of the seeds for the policy and personality clashes as the war and the bombing offensive developed. A comment by AOC 3 Group (Air Marshal Baldwin) concerning Bufton was that:
Perhaps he (Bufton) had allowed his suspicions of Group and Operational Commanders to get the better of him!
The subsequent operational achievements of the PFF are sincerely acknowledged. This section very briefly addresses the contribution of the PFF to bombing accuracy within the context of ‘precision versus area’ bombing operations. Air Vice Marshal D Bennett was to become AOC No. 8 (PFF) Group. He had been closely associated with the formation of Ferry Command to fly aircraft from Canada to the UK; he had flown operational bombing missions and had been shot down over Norway in 1942. He walked out to Sweden.
The operational objective of the PFF was to mark the required target(s) with coloured flares. The actual position of those flares could then be designated in relation to the required target(s), if necessary, and the following main bomber force would aim either at the flares or at a specified offset aiming point. Some techniques used ground-marker flares with the codewords PARAMATTA or NEWHAVEN, otherwise known as Target Indicators; others used airborne sky-marker flares, with the codeword WANGANUI. The latter would be used when there was cloud cover of the target(s) or smoke obscuration; but such flares were never stationary – they were falling and drifting with the wind; and the wind vector may be quite different between the bomber and the flare altitudes. When a bomb aimer was using a sky-marker flare(s) as his aiming point, that flare was initially well above the real target and the bomb would still have some forward carry in its ballistic path. This aspect of the PFF operation is discussed in the reference. There was a great deal of concern and assessment of the accuracy of flares and their delivery by the PFF. Major matters related to accurate timing of flare release and the subsequent arrival of the Main Force bombers; the Recommended Air Speed and altitude for those bombers, with particular regard to the cruise speed and the speed loss with open bomb doors; and the importance of maintaining the correct aircraft heading.
The concept of a Master Bomber was introduced later in the war against important targets, initially advocated by AVM The Hon. Cochrane of 5 Group during the summer of 1943. That task required the Master Bomber to remain over the target area and issue directions for additional markers and/or bombing offsets as the raid developed.
The practice of low-level target marking also gained some value and notoriety. Partly that was because one of the main enthusiasts was AVM Cochrane and an accomplished exponent was Gp Capt. Leonard Cheshire, VC. No. 5 Group had always had a certain individuality and no lack of skill. Low level target marking was difficult and dangerous but it could be very effective when the weather and visibility conditions were suitable.
The operational use of flares by the PFF was not simple. The following text shown below in italics is extracted from the pre-flight briefing for a raid on Essen during the night of 4/5 Jan 43:
Four Mosquitoes of PFF and 30 Lancasters of No. 1Group will carry out a blind bombing attack with the aid of navigational and sky-marker flares. The Mosquitoes will operate in two sections of two aircraft; both pairs will carry out exactly the same procedure. The first from 1936 to 1940 hours and the second from 1938 to 1942 hours.
Preliminary warning flares (Green steady) will be released by the first pair at 1936 at a position approximately 5150N 0657E, four minutes before the Sky-marker flares which indicate the point of bomb release. Secondary warning flares will be dropped at 1938.The release-point flares themselves (Green with Red stars) will be dropped at 1940. The whole procedure will be repeated two minutes later by the second pair of Mosquitoes, whose release-point flares will be dropped at 1942 hours; these release-point flares will burn for two minutes. At that time White marker flares will start to burn for the emergency use of latecomers, who should approach them on the correct heading (170º magnetic) but should release their bombs about 2 miles short of the flares at the start of their burning period – increasing by a further mile for every minute later.
The Lancasters are to approach the release-point flares on an exact heading of 170º magnetic. When on this heading, the preliminary Green flares should be exactly on the port beam at a distance of five miles and the secondary Red flares should be to port and slightly ahead at a distance of 2½ miles. Each Lancaster will carry 1x4000lb GP Bomb which is to be dropped when exactly over the release-point flares; and ten containers of 4lb Incendiaries, which are to be released ten seconds after the HE bomb on the same heading. All aircraft are to maintain 20,000ft over the defended areas. The success of this operation depends on accurate timing.
The purpose of outlining that pre-flight briefing was to demonstrate the basic process of marker flare release and the subsequent actions by the bomber force; there is nothing extraordinary about that example. It was a small simple raid but it shows the most critical factors: flare release point accuracy, the correct heading of the main force bomber aircraft and precise timing. All of these factors demanded a high level of skill and there is no allowance for the distraction of combat or the effect of the winds on the actual position of the sky-marker flares.
Within the same folder Air 14/2984, there are many other examples of preflight briefing details; subsequent post-flight analyses made on the basis of night photography taken at the time; and later PR to disclose damage effects. These analyses did not make good reading but their purpose was to examine what actually happened and to recommend improvements in PFF and bombing techniques, as operational experience was gathered. The sort of problems that arose included:
H2S and Ground Marking Attack – Turin 4/5 Feb 43. It had been hoped that well-placed Target Indicating markers would overcome the tendency for the main weight of attack to be offset from the aiming point. Visibility was good. The evidence showed that the TI markers were scattered and that the bombing followed that scattering, with the weight of attack falling on the Western edge of the town some two miles West of the aiming point. It was determined that the initial undershoot of the TI markers was a consequence of incorrect allowance for forward throw; and there was successive ‘creep back’ of subsequent markers.
H2S and Sky Marking Attack – Wilhelmshaven 18/19 Feb 43. Visibility was reported as excellent and crews claimed to have had no difficulty in recognising the area; but there was a very strong westerly wind (60–80 mph) at the operational height. The evidence indicated that the weight of attack fell almost entirely in open country 2–6 miles west of the target, with negligible damage in the town. Only 4 out of the 13 H2S aircraft found it possible to home onto the aiming point, and those 4 crews also checked the position visually. The key problem was that the marker aircraft were not on schedule. The first markers were closest to the aiming point and then there was a progressive displacement to the west-southwest. This was compounded by enemy smoke screens and dummy markers, the visual effect of which was aggravated by moonlight reflections. Another problem related to the use of H2S was that new construction work in the area may have generated an unexpected echo that was uncorrelated with the available maps.
Harris expressed his view about Schweinfurt as a target in a letter dated 9 Jan 44, to the Under-Secretary of State for Air and to Bottomley. Harris wrote that Schweinfurt was a small, well-defended target which was difficult to locate at night; not only did Bomber Command lack the navigation and bombing aids to locate and attack that target, but he doubted if the PFF could position the visual bombing flares with sufficient accuracy. After further exhortation from the Air Staff, Harris did order a night raid on Schweinfurt on 24/25 Feb 44 that followed a daylight raid by the 8th USAAF on 24 Feb 44. The raid was not a success. The PFF first visual target marker aircraft reported no trouble in marking the aiming point but subsequent markers were short of the target and spread back to the south-west. That tendency to ‘creep back’ was a known problem. There was one further raid on the night of 26/27 Apr 44 by 215 Lancasters and eleven Mosquitoes. That was also unsuccessful; the low level target marking was inaccurate and strong winds disrupted the Main Force timing over the target.
‘Creep back’ was a rather persistent problem in the bomb impact points as the raids developed. There was a tendency for bombers that were following the leading aircraft to aim towards the rear either of the marker flares or the fires from the immediately preceding bombs; the effect was that the bomb impact point tended to moved backwards away from the true aiming point or target. Training and practice reduced this problem but the visual distraction of multiple fires, not least decoy fires lit by the enemy, was always a problem. The PR Interpretation Report N.128 dated 28 Jun 43 is an example of the analysis that was conducted by the CIU into the enemy use of decoy fires. These problems could not be eliminated, whether they arose as a direct consequence of decoys or as target identification errors when other bombs or flares had fallen in the wrong place.
Target marking techniques were a subject of constant review and improvement. During May and Jun 44, Sir Arthur Harris and AOC 5 Group discussed the use of Mosquitoes for low-level offset marking of targets in the Ruhr – backed up by Lancasters.80 The point was made that even the Mosquito was rather too vulnerable to light flak at low altitude where there was heavy searchlight coverage. Gp Capt. Cheshire had suggested that a better aircraft would be a single seat long-range fighter, such as a Mustang or Typhoon. Cheshire thought that such an aircraft would allow accurate low-level marking and that this would be particularly useful beyond the range of the ground-based navigation aids such as Oboe, albeit subject to weather conditions en-route and in the target area. This was very much associated with the improved techniques of the Master Bombers, who could then use PFF Lancasters to back-up these low-level markers. Arrangements were made between Bomber Command and the USAAF for the loan of a Mustang to experiment with low-level target marking; a better option was seen to be the P-38 Lightning, which carried a two-man crew and had two engines with contra-rotating propellers that gave much better flight stability and better range.
Even late in the war, the operational use of target marking was not without problems as the political and military need for increased bombing accuracy became more intense. Sir Arthur Harris wrote to the CAS in response to a draft bombing policy from the Deputy Supreme Commander Tedder:
Area bombing must enter into any scheme because in bad weather we have to use sky-markers and we must have a large target within Oboe or G-H range. In those conditions we necessarily paint with a large brush.
There is however another aspect of bombing which it is always difficult to impress or to keep impressed upon those outside the immediate Command; and that is the decisive effect of weather and tactical factors on what can be done at any given moment. Taking account of the altitude ceilings of our bombers and the winter cloud formations with high icing indices, it is often impossible to go where one wants to go.
Given the statistical pattern of Bomb Impact Points there would have been perhaps many occasions when a single bomb scored a direct hit on the intended target, but this cannot be claimed as an example of ‘precision bombing’. It was no more than a matter of chance. There is however absolutely no doubt that the PFF provided the means of significantly improving average bombing accuracy.