How Bomber Command Helped Win The Battle Of Britain
By Neil Young
The RAF's victory over the Luftwaffe during the Battle of Britain in
the summer of 1940 made a German invasion of Britain all but impossible.
In his book Bomber Offensive, published in 1947, Marshal of the Royal Air
Force Sir Arthur Harris wrote that all the credit for preventing the invasion
of Britain had been given to Fighter Command. He felt that the influence
and importance of Bomber Command's role in the Battle of Britain had been
largely overlooked. Germany's failure to defeat the RAF and secure control
of the skies over southern England convinced Hitler to indefinitely postpone
the planned invasion of Britain. While this victory was decisively gained
by Britain's fighter defences, other organisations also contributed.
During the Battle of Britain, Bomber Command suffered from fundamental
disagreements within the military and political leadership about how it
was best employed, as well as from multiple and often conflicting demands
upon its relatively limited resources. In the years before the Second World
War, the development of the RAF was dominated by the belief that the service
would be best employed in a strategic air offensive against Germany. A
series of 'Western Air Plans' was formulated, listing strategic targets
for attack. The offensive began on 15 May 1940, five days after the German
invasion of France and the Low Countries, and would last until virtually
the end of the war. It was, for some years, the only means of taking the
war directly to Germany itself. However, with the prospect of air attack
and invasion, Bomber Command was beset by conflicting demands upon its
At first, Bomber Command's main objective was the reduction of the threat
from the German air force against Britain. Whitley, Wellington and Hampden
heavy bombers were to attack German aircraft factories and assembly plants
by night and Blenheim medium bombers would raid aerodromes in occupied
territory by day. When, from late August onwards, German shipping began
to concentrate in preparation for an invasion of Britain, ports from northern
Germany to the French Channel coast became the primary targets. However,
in directives issued by the Air Ministry throughout the summer, due regard
was still paid to the strategic offensive. Attacks were ordered on the
oil industry, communications, forests and crops. Minelaying in German coastal
waters was also to be undertaken. These objectives enjoyed varying priority
at different times.
Such a multiplicity of targets ensured that concentration of effort
could not be brought to bear against any one in particular. Moreover, poor
navigation and bombing techniques as well as a lack of knowledge and an
over-optimistic view of the results of bombing made Bomber Command's early
operations mostly very ineffective. Night-time raids on inland targets
were impossible without bright moonlight, and even then these targets were
difficult to find. Raids against invasion ports, because of their proximity
to Britain and easily found positions, were much more successful.
At the beginning of May, before the German invasion of France and the
Low Countries, the Chiefs of Staff (COS) Committee reviewed the strategic
situation on the assumption that Germany would seek a decision in 1940.
Of the two possible ways of achieving this - major attacks on either Britain
or France - the Chiefs of Staff thought attacks on Britain more likely.
The main threat to the United Kingdom's security would thus come from an
intensive German air offensive. Although it was expected that serious material
damage and dislocation would be caused to Britain's air force and aircraft
industry, it was thought that the Luftwaffe would not succeed in its vital
aim of neutralising the RAF's air striking force. It was essential, the
COS concluded, that all possible measures should be taken to expedite the
production of anti-aircraft equipment and bomber and fighter aircraft,
even at the expense of the country's long-term armament programme.
A mere three weeks later, in light of the German invasion of France
and the Low Countries, the COS had to re-examine British strategy in case
of the complete collapse of French resistance. It was clear that Britain
would be subjected to the concentrated attack of German air and naval forces
operating at the shortest possible range from Norway to France. Undoubtedly,
the key role in the successful repulsion of this grave threat would be
played by British fighter squadrons. But, as the COS wrote in a report
on 25 May, 'we cannot resist invasion by fighter aircraft alone. An air
striking force is necessary not only to meet the sea-borne expedition,
but also to bring direct pressure to bear upon Germany by attacking objectives
in that country'.
On 20 June, a few days after the fall of France, Bomber Command's Commander-in-Chief
Air Marshal Charles Portal was directed by the Air Ministry to launch his
striking force primarily against objectives that would result in the immediate
reduction of the scale of German air attacks against Britain. The directive
listed airframe assembly factories, aluminium plants and equipment depots
within range in Germany as the most urgent targets, though some members
of the Air Staff had reservations about the first of these. It was felt
that the destruction of assembly factories would not appreciably reduce
the effort of the Luftwaffe because the level of its reserves would ensure
attacks could be maintained at full intensity during the period in which
the factories were re-established out of range. However, attacks on the
main equipment and maintenance depots would have an immediate effect as
these units were organised to provide major maintenance facilities for
front line squadrons and the fitting out and supply of reserve aircraft
to replace wreckage.
It was thought that German communications were fully stretched in distributing
supplies to forward areas. The directive to Portal therefore ordered him
to assault railways and canals. The principal focus of attack should be
the marshalling yards of the Ruhr and Cologne areas, in particular the
main yard at Hamm, and the aqueducts carrying the Dortmund-Ems canal over
the River Ems near Munster. One squadron was also to continue laying mines
in German coastal waters. Subject to these primary tasks, operations were
to continue against oil targets, especially all major stocks in the newly-occupied
territories before they could be utilised by enemy forces. Preparations
were also to be made to set alight German crops and forests using a new
incendiary pellet that would be ready in early July. Bomber Command's medium
bomber squadrons were to attack enemy occupied airfields in northern France
and the Low Countries in order to destroy as many aircraft as possible
and force the rest to withdraw to locations in the rear. Finally, Portal
was directed that he should be prepared at short notice to divert all his
bombers against an invading enemy naval force.
Fears of invasion were increasing rapidly. Prime Minister Winston Churchill
told the Cabinet on 3 July that there was a growing feeling that an attempt
might be imminent. He appreciated the reasons put forward by the Chief
of the Air Staff (CAS), Air Chief Marshal Sir Cyril Newall, for the RAF's
present concentration on the German aircraft industry, but considered that
the coming week might be so critical that it justified transferring priority
to the bombing of enemy harbours and shipping.
The following day, Portal was directed to make these targets his first
concern, with particular emphasis on Kiel, where the capital ships Scharnhorst
and Deutschland were berthed, as well as Hamburg, Bremen, Rotterdam, Wilhelmshaven
and Brunsbuttel. The minelaying deployment was increased to three squadrons
and the offensive against the aircraft industry and oil was to be maintained.
Though initially dropped, after discussion between Portal and Deputy CAS
Air Vice-Marshal Sir William Sholto Douglas it was agreed that the effort
against communications should continue in a limited way.
For the Blenheims of 2 Group, the priorities would now be: the attacking
of barges and small craft on the canals and in the ports of Holland and
Belgium, the continued daytime disturbance of targets attacked in Germany
by night, and raids against concentrations of aircraft at aerodromes in
north-west France and Belgium and shipping reported in Norwegian ports.
Because of the high vulnerability of aircraft engaged in day bombing, attacks
were to be made sporadically and only when adequate security through sufficient
cloud cover was available. 2 Group was to employ up to 48 aircraft per
day, operating individually or in small groups. Every effort was to be
made to spread attacks so that the resulting calls for German fighter protection
would be widespread and numerous, keeping the fighter defences dispersed.
The threat of immediate invasion receded somewhat when it became apparent
that Germany was concentrating increasingly on preliminary air attacks
against Britain. The Air Staff considered that operations up to this point
had been too dispersed and issued a corrective order on 13 July, which
went to the heart of the problem of Bomber Command's operational effectiveness.
The Air Staff now requested that fewer targets be attacked more vigorously
with the aim of complete destruction, not harassment. Only five airframe
assembly factories, five equipment depots and five oil plants were selected
as primary targets.
When he received the directive, Air Marshal (now Sir Charles) Portal
was provoked into a detailed and lengthy criticism of the difficulties
of applying it. Very few of the objectives would be found by average crews,
while even expert crews would require the help of clear nights with a full
moon to succeed. Most of the targets were isolated and in sparsely inhabited
areas far to the east in Germany. Therefore, he expected a high percentage
of wasted effort in searching for and reaching them, while those bombs
which were badly aimed would hit nothing else of importance.
Portal believed the most effective way to realise Bomber Command's aim
of reducing the scale of air attack on Britain was to cause dislocation
to the largest possible number of factories by periodic assaults rather
than attempting to obliterate a select few. This was partially because
the obliterated target exercised no moral effect once the factory workers
had been removed and it could always be rebuilt in a safer area. He responded
to the charge that the effort of his Command had been too greatly dispersed
by explaining that tactical factors, such as the weather and limited amounts
of darkness, often made it unavoidable. However, he also saw virtue in
this as the scatter attacks spread alarm and disturbance over a wide area.
Portal also pointed out that the designation of communications as 'last
resort' targets was unrealistic. The value of such targets depended almost
entirely on their geographical location and visibility, and therefore they
should always be between the primary objective and the home base.
The day following his letter to the Air Ministry, Portal wrote another
to Douglas, which he described as 'entirely personal' in order to express
the views he could not say in his official capacity. He felt that the selection
of such a narrow aim as the reduction of the scale of air attack on Britain
by the Air Staff was a 'tremendous mistake' and questioned whether attacks
on aircraft factories had any effect on limiting the German air effort
at all. Portal wanted a much more positive role for Bomber Command, which
he saw as 'the one directly offensive weapon in the whole of our armoury'.
Therefore he suggested to Douglas that the RAF should take as its aim the
greatest possible disruption of German war industry with the greatest possible
Douglas, in summarising Portal's letter to the CAS on 20 July, suggested
that a meeting be held with the C-in-C. In an agenda for this forthcoming
conference, the Air Staff made clear their unease with Portal's position.
His desire to attack wide ranging targets periodically, in preference to
obliterating a select few, appeared in direct conflict with the principle
of concentration, upon which their offensive plans were based.
It was the Air Staff's belief that moral effect, despite being an extremely
important subsidiary result of bombing, could not be decisive - material
destruction had to be the primary object. Moreover, it was crucially important
to continue the offensive against Germany's aircraft industry. The Air
Staff appreciated the tactical and operational constraints of Bomber Command
and conceded that too restricted a list of objectives might have been given.
But they also hoped to avoid the wide dispersion of former directives to
give Portal a limited number of targets on which to concentrate his force
during the current phase of operations.
The conference between Portal and the Air Staff made little difference
to Bomber Command's objectives which, in a new directive issued on 24 July,
remained the reduction of the scale of air attack on Britain. However,
in deference to Portal, the number of primary targets was increased and
the offensive against oil was raised again to second priority. Portal's
opposition to the Air Staff's defensive bombing policy and its failure
to unleash the full potential of the strategic air offensive did not bear
fruit until the autumn, after the Battle of Britain was over and not until
he himself became Chief of the Air Staff. Portal's mind was soon changed
abruptly, but briefly, as the German air assault began to intensify in
Churchill was alive to the political and propaganda possibilities of
the course of the Battle of Britain. He asked Secretary of State for Air
Sir Archibald Sinclair whether, in case of a German raid on London, the
RAF had the capability to reply immediately against Berlin. Sinclair replied
on 23 July that the Hampden, Wellington and Whitley heavy bombers, and
the Blenheims with a light load, could all reach the German capital. A
limited capability was available at once, but from 2 August the whole of
the heavy bomber force could be employed. With 12 hours' notice, 65 to
70 tons could be dropped and repeated every night for a week. With 24 hours'
notice the bomb lift could be increased from 130 to 150 tons, repeated
every alternative night for a week. If a heavy single blow was desired,
the bomb-load could rise to 200 tons.
At the end of July, however, anti-invasion preparations were of the
greater moment. Both the COS Committee and the Air Staff agreed that to
attempt and sustain an invasion, Germany would have to gain air supremacy
over the areas where it would require secure sea communications between
the continent and the British coast. Therefore, while Bomber Command would
continue to reduce the scale of German air attack by striking at suitable
objectives in Germany, it would also be prepared to divert its efforts
to the attack of enemy shipping concentrations, especially troop-carrying
vessels, should these materialise. If a seaborne invasion was launched,
Bomber Command would attack transports at sea and at landing points.
During August, as the Battle of Britain became more fiercely joined,
Bomber Command's effort against the German air force increased accordingly.
Of the 2,227 sorties it flew in the month, 714 were against aerodromes
in occupied Europe, almost twice as many as in July, and 435 against the
German aircraft industry. Until 12 August, the Blenheim squadrons of 2
Group attempted day operations but, due to heavy losses, had to revert
to night raids. On 17 August, the Air Ministry called on Bomber Command
for increased attacks against those aerodromes in occupied Europe from
which the enemy's air assault was being launched.
Owing to the paucity of reconnaissance reports, it proved very difficult
to assess the results of these attacks. Moreover, doubts had always been
held by some members of the Air Staff about the uneconomical nature of
airfields as targets. German attacks were launched from some 400 different
aerodromes in northern France, Holland and Belgium and the Luftwaffe operated
efficient dispersal and protective schemes. Therefore, Bomber Command never
knew before launching raids which of the aerodromes were actually in operation.
The inadvertent bombing of London by German aircraft of 24 August provoked
immediate retaliation by Bomber Command against Berlin the following night.
More raids in the same week and the general damage caused to German cities
by the air offensive were contributory factors in the Luftwaffe's change
of air attack priority from Fighter Command's airfields to London on 7
September, the turning point of the Battle of Britain. On 29 August, Churchill
told the Cabinet he proposed sending a message of congratulations to Bomber
Command on the bombing of Berlin. In view of the indiscriminate bombing
by the Germans, it was possible that, in the near future, the Government
might have to consider a temporary but marked departure from its policy
of bombing only military targets.
At the beginning of September, the Prime Minister suggested to Portal
that the bombing offensive should now be spread as widely as possible over
those German cities and small towns within Bomber Command's reach. The
Vice-Chief of the Air Staff, Air Marshal Sir Richard Peirse, pointed out
to Churchill that such a plan had been devised already for use in the winter
when unfavourable weather conditions might prevent the precise bombing
of targets. However, the Air Staff preferred not to disperse its effort
on to other targets, but to continue with the offensive against German
aircraft industry, oil and communications objectives. Peirse contrasted
what the Air Staff believed to be the effectiveness of the RAF's bombing,
which was planned and relentless until a particular objective was considered
to have been destroyed or dislocated, with the German effort, which was
sporadic and mainly harassing. Moral effect was not gained by harassing,
he told Churchill, but was proportionate to the material damage done. The
complete destruction of a target was therefore the best way to cripple
Political pressure for retaliation against German indiscriminate bombing
continued. On 10 September, the Cabinet agreed that Bomber Command's aircraft
should be instructed not to return home with their bombs if they failed
to find their primary targets. However, two days later Churchill allowed
an earlier Air Ministry signal, issued before the Cabinet meeting, to stand.
It instructed Bomber Command that it was not the intention to bomb at random
nor that pilots should never bring back their bombs. But it also made clear
that every attempt was to be made to bomb alternative or last resort targets
On 19 September, Churchill told the COS Committee that the dropping
of large parachute mines by the Luftwaffe proved the Germans' intention
to perpetrate an 'act of terror' against the British civil population.
He wanted preparations made for equal retaliation to be inflicted on ordinary
German cities. The Cabinet agreed that aerial mines should be dropped on
Berlin and on 21 September the COS replied that they were in favour of
giving the German population 'a taste of their own medicine'.
These demands were initially resisted by the Air Staff. They pointed
out that, because Bomber Command was considered capable of precision attacks,
indiscriminate bombing was unnecessary and futile. Moreover, it would be
unwise to start competitive bombing when the Luftwaffe's striking force
was four times larger than the RAF's and, to reach Berlin, British aircraft
had five times as far to travel as German aircraft had to reach London.
However, as a reply to the bombing of London, a raid of the largest possible
scale on Berlin was ordered and carried out by 119 aircraft on 23-24 September.
The Air Staff directive of 21 September instructed Bomber Command that,
although there were no objectives in the area of strategic importance,
periodic attacks on Berlin were to continue in order 'to cause the greatest
possible disturbance and dislocation' to industry and the civil population.
The quickest, most lasting and effective means of achieving this would
be by attacks on sources of power. Nevertheless, the directive reiterated
the Air Staff's view that in accordance with long-term offensive strategy,
focus should remain on destroying German oil resources and communications.
Bomber Command was requested to continue to deploy a proportion of its
effort against these objectives, despite the intensive operations being
taken against German invasion preparations.
The Air Staff's line of thinking was not met with complete agreement
by Bomber Command. Churchill's suggestions were received with greater sympathy
by Portal, who returned to the ideas he had advocated in July. On 11 September
he told the Air Ministry that each indiscriminate Luftwaffe attack on a
British town should be answered in kind by the RAF. A Bomber Command memorandum
of 30 September expressed the view that the strategic offensive should
now be directed at 'the will of the German people'.
These developments in policy had implications for the long-term execution
of the strategic air offensive throughout the rest of the war and are therefore
of high significance. However, the role for which Bomber Command was of
greatest value during the summer of 1940 was its contribution to the prevention
of a German invasion of Britain. In September, the threat of invasion grew
to such proportions that sixty per cent of Bomber Command's effort was
deployed against invasion targets. In the first days of the month, extensive
movements of shipping began from north German ports to embarkation harbours
in Belgium and France. On 5 September, the RAF made its first major raids
against these concentrations. Two days later, with the issue of an invasion
alert, the Air Ministry signalled to Bomber Command that 'all available
bomber effort' for the night's operations was to be directed against invasion
shipping. Hourly reconnaissance between 10.00pm and 4.00am the following
morning were required to identify any movement of barges or shipping in
or out of the harbours at Ostend, Nieuport, Dunkirk, Calais and Boulogne.
As September progressed, so the level of Bomber Command's attack increased.
On the night of 13-14, the whole of the available bomber force was dispatched
against the barges. The following night the number of sorties rose to 176
and again to 192 on 17 September. The operations enjoyed greater success
than those aimed at Bomber Command's other targets.
The extent of the threat of invasion was outlined in the Joint Planning
Staff's (JPS) report of 18 September. The JPS considered that the Germans
had 'virtually unlimited' numbers of barges for a short sea crossing, which
could transport 150,000 men with their equipment and four days' supplies.
Taking into account considerations of wind, tide and the average speed
of the barges, it was thought possible for craft from all ports between
Ostend and Boulogne to reach the Kent coast moving by night. Despite the
immense navigational difficulties and the possibility of sinking many barges
during the crossing, the JPS expected large numbers to arrive on British
On 20 September, Air Commodore N H Bottomley, Senior Air Staff Officer
at Bomber Command, informed Portal that the JPS indicated that the most
vulnerable time for a German seaborne expedition would be during the landing
period, when running up to and discharging on the beaches. Bottomley thought
the memorandum failed to stress the vulnerability of a barge borne expedition
at the ports of concentration. He advocated taking advantage of the prevailing
moon conditions and sending Wellington heavy bombers on two sorties a night
with maximum loads. Bomber Command's Whitley squadrons could thereby be
released to fulfil the Air Ministry's desire to continue the attack on
objectives in Germany. Portal replied the next day that he agreed, except
that it would be better to work all crews three nights running than twice
in one night.
'In the immediate future, while the imminent threat of invasion remains',
the Air Ministry Directive of 21 September explained, 'the greater part
of the bomber effort must continue to be employed against anti-invasion
objectives'. The primary aim of Bomber Command would be the destruction
of the major concentrations of shipping at enemy ports, with the secondary
object of harassing facilities and communications within and adjoining
the ports so as to dislocate the mounting and despatch of the invasion.
Because it was believed that German invasion preparations were complete,
and with the current operational emphasis on ports and shipping, the Air
Ministry felt that the attacks on the German aircraft industry no longer
had any immediate effect on the present situation. As a longer term policy,
but one likely to have a more lasting impact on the German air force during
the coming winter and early months of 1941, Bomber Command was directed
to attack aluminium plants and key component factories.
On 17 September, just as Bomber Command's effort against invasion targets
was reaching its height, Hitler postponed the invasion. The subsequent
dispersal of German shipping was soon noticed by Coastal Command's photographic
reconnaissance aircraft and on 30 September, the Air Ministry signalled
Bomber Command that the imminence of invasion had 'somewhat receded'. In
such circumstances, particularly when weather conditions were unsuitable
for cross-Channel operations, authority was now given to increase efforts
against objectives in Germany in compliance with the instructions given
in the directive of 21 September
By October 1940, the failure of the Luftwaffe to eliminate Britain's
fighter aircraft defences and win control of the skies over the English
Channel and southern England ensured that the vital pre-conditions for
a successful invasion of Britain had not been met. Fighter Command had
won the Battle of Britain. However, the effectiveness of Bomber Command's
attacks on the enemy's invasion ports and shipping had made an important
contribution to the victory. Although only ten per cent of the assembled
barges and other vessels had been destroyed, Bomber Command had caused
the Germans great difficulty in gathering an invasion fleet and demonstrated
the futility of attempting to launch a seaborne invasion across the Channel.
Bomber Command, fashioned as the instrument of the strategic offensive,
had been pre-occupied with the threat of invasion and the reduction of
the scale of German air attack throughout the Battle of Britain. Nevertheless,
as the Air Ministry had been determined to continue the long term assault
on German industry, Bomber Command undertook as many strategic operations
as possible. The effect on the German economy in 1940, however, was negligible.
The targets selected were too many and various for the small bomber force
then available. Navigation and target location techniques were so inadequate
that it was not unusual for aircraft to bomb not only the wrong factory
but also the wrong city. Most unfortunately, the Air Staff and Bomber Command
were completely unaware that their optimistic appraisals of the damage
caused to German industry were grossly exaggerated. Not until after the
Battle of Britain was over did night photography of bomber operations and
photographic reconnaissance begin to become available and not until 1941
was it realised that these types of damage assessment were the only accurate
and worthwhile methods.
The growing realisation of these problems led the Air Ministry, particularly
after the appointment of Portal as Chief of the Air Staff in October 1940,
to move from a policy which placed less emphasis on precision bombing of
targets to one which selected objectives that were not isolated but, if
possible, grouped within large centres of population or industry.
A longer version of this article, written by Neil Young (former IWM
Historian), appeared in the Imperial War Museum Review, No. 6 (1991).