An Air Staff memorandum (July 30th 1940) on seaborne invasion reasoned that Germany would have to gain air supremacy in order to secure her lines of sea communication. With the invasion of France Germany could now concentrate her whole air force against Britain. Consequently it assumed (correctly as events soon proved) that the first phase of any invasion attempt would be a large scale air offensive against fighter aerodromes and organization and factories. It was also probable that Germany may attempt to weaken the Navy by attacks on naval bases on the East and South-east coasts.
In this first phase of operations the role of Fighter Command was to meet the attacks on its organization and aircraft industry. Fighter Command would also have to meet air attacks on Naval bases although the priority of fighter action in support of Naval bases or aerodromes etc would have to be dealt with on case by case basis.
In order to meet this expected air offensive it was planned to raise the number of fighter squadrons from the present 59 to 70. An additional 10 fighter sectors were proposed (mainly in the South-west and North-west) to be added to the Aircraft Fighting Zone and 3,900 searchlights were in place in the Zone and Gun Defended Areas (out of an approved 4,128). To detect low flying aircraft a series of ‘Chain Home Low’ stations were added to the existing network of ‘Chain Home’ R.D.F stations – by mid-June 19 were in place out of a planned 21. Aerodromes were dispersed as widely as possible and provided with satellite landing grounds as well as a full compliment of AA guns, stripped from places that could best afford to lose them and production centers not considered to be of primary importance – for example London’s AA guns were reduced from 114 to 92 in July (although they were bought back during September as a result of The Blitz). From the launch of ‘Alderangriff’ on Aug 13th Fighter Command was fully occupied in trying to defeat the air offensive.
Top - British Fighters. Left - Spitfires. Right - Hurricanes
Middle - German Fighters. Left - Me 109. Right - Me 110. This suffered heavy losses in the Battle of Britain but was to prove itself as a night fighter.
Bottom - German bombers that Fighter Command had to defeat. Left - Heinkel 111. Middle - Dornier 17. Right - Ju 88.
Germany had already demonstrated some success in the use of airborne forces and it was considered she may attempt a large airborne raid either on a remote part of Britain or in an attempt to seize a port. Fighter Command's role in this phase was to destroy tank carrying aircraft, troop carrying aircraft, bombers and fighters in this order of priority. Should an airborne and seaborne expedition occur simultaneously, the protection of naval forces would rank equally with destroying an airborne landing in the vicinity of a port, these two requirements taking precedence of airborne landings elsewhere.
Should Germany decide that the only way to defeat Britain was to launch a seaborne invasion, the invasion would be in three phases:
- I Concentration of troops and shipping at points of departure
- II The voyage from continental coasts to the British coast
- III The establishment of a bridge head in Britain.
Fighter Command's role would be to provide as far as possible fighter escort for bombing attacks against the points of departure of the invasion fleet.
As any seaborne invasion could not succeed unless the Royal Navy was seriously weakened, Fighter Command's primary role would be to give protection to naval vessels(especially from enemy dive bombers) engaged in destroying enemy transports and a secondary role to provide protection for bombers engaged in attacks against enemy vessels.
This phase would probably involve a simultaneous airborne attack with a continued effort by the enemy to gain and maintain air supremacy over the area of invasion. The primary role was to defeat the seaborne invasion so targets for Fighter Command in order of priority would be:
- Dive bombers operating against naval forces
- Tank carrying aircraft
- Troop carrying aircraft
Above: Stuka Dive Bombers - considered to be the greatest threat to Naval vessels operating against the invasion flotillas.
During the evacuation of Dunkirk, the RAF was often criticized for its absence. However this was not the reality of the situation as the majority of fighters were employed not over the beaches but in trying to shoot down bombers before they could reach the beaches. A memorandum was produced to explain the best use of fighters to the Army commanders so that they would not expect them to be employed in areas were there activities would be of secondary value.
If a bomber travelled at 240 mph and had a 12 minute start, a fighter travelling at 300 mph would have to travel 200 miles to catch up with the bomber. If a bomber was attacking troops they would expect to see fighters in support, but this would not prevent the bombing although the fighter may shoot down the bomber after it had dropped its bombs. The fighter would need time to sight, catch up with and shoot down bombers before they reached the point where their bomb loads were released.
Defence Plans for the United Kingdom, TNA
Invasion Memoranda, Air Ministry, TNA