Douglas Haig has been called home to discuss the war effort. He has been told that following the raid on London on 13 June, the public outcry has been such that the Government will be discussing home defence. Hugh Trenchard, Commander of the RFC was asked to set down his thoughts on defending the coast.
He set them down today to an HQ memorandum to Haig:
“METHODS SUGGESTED FOR THE PREVENTING OF AIR RAIDS IN THE UNITED KINGDOM [Memorandum of Major-General H. M. Trenchard, prepared for the Commander-in-Chief, June 1917]
Before attempting to lay down methods, the following points must be understood
(a) To keep one machine in the air all day requires five machines and five pilots at least.
(b) It is no good suggesting methods which the present limitation of aircraft would prevent being carried out regularly and systematically, such as choosing an objective outside the normal range of the machine.
(c) The least effective and most expensive way of protecting a place like London is to have constant patrols. (d) The limitation of the output of pilots, machines, and engines owing first to the shortage of labour and secondly to the shortage of raw material.
The following methods are suggested:
1. To capture the Belgian Coast up to Holland
2. Landing people with explosives to set fire to sheds at night
1. Capture of the Coast
With regard to this, the advantages are:
(a) If the coast was captured the German machines would then have to cross our lines or pass over neutral country. If they crossed our lines they would be engaged by our anti-aircraft guns; they would have to pass over our aerodromes, and our fast machines would be able to see them and go up and engage them over the latter long before they got to England. The Germans would also have to come back the same way, again being engaged both by aeroplanes and anti-aircraft guns.
(b) They would also be more easily seen and warnings could be sent to England.
(c) Their landing-grounds would be further away from England.
2. Landing People at Night
The advantages of this system are:
(a) Very few machines are required to do this. Two or three machines could land in the vicinity of a big aerodrome on a really good moonlight night and set fire to the sheds.
(b) If these big bombing machines which the Germans are using could be burnt, it would take some considerable time to provide new ones.
The disadvantages are:
(a) It could not be done except on a good night.
(b) It is impossible to say on which aerodrome the machines might be. Even if a squadron is located at one aerodrome, there is nothing to prevent it from moving to another unknown to us.
(c) If the sheds were set alight and destroyed it would only be possible to do this once or twice before the sheds were heavily protected and if unsuccessful the first time it would probably fail again at subsequent attempts.
(d) The man landed would have to trust to get through to Holland to get away and probably this would be impossible, but no doubt we could get volunteers for it.
3. Reprisals (by a few machines or by large organized squadrons).
The advantages of this method are
(a) The German population is more easily moved by having their own country touched than the English population
(b) The first method is to use a few machines which could be made available in England and sent out to us here to go long distances such as to Aix-la-Chapelle, Cologne, Coblenz and to send one or two of these machines with selected pilots to drop bombs and papers warning them that more machines would be sent as was done in the case of the French bombing raid on Freiburg. This might have some effect without entail- ing the use of large forces as single machines would have a greater chance of getting through and back again without being seen, and this could be done at once.
(c) The G.O.C. the German Flying Corps has stated that the distant towns are out of reach of British machines, and he has assured the whole country of this. (d) This might have a great effect on the enemy as it might make him withdraw a certain number of machines, and certainly withdraw pilots for the local defence of towns.
The disadvantages are
(a) There are no army machines in France with sufficient range to be able to carry out raids on Prussian towns, but this difficulty would be got over by improvised machines. There are a certain number of machines in this country that would be able to carry out raids on the Southern German towns such as Freiburg, but there are machines which could be provided from home, if the information I have been supplied with is correct (such as the De Hav. 4 with B.H.P. engine and 5 J hours petrol), but these machines could not bomb the far distant towns except on favourable occasions.
(b) To organize bombing squadrons with a large range on a large scale would take a considerable time.
(c) Another disadvantage of reprisals is they would only lead to further reprisals from the enemy. We must be prepared, if reprisal methods are to be adopted, to carry it through and outlast the enemy. They would always defeat us at reprisals unless we put forth our whole energy and this would seriously interfere with the supply of the machines necessary for artillery work.
I will discuss these rather generally from the point of view of three possible systems
(a) Constant patrols protecting London, the English Coast, or the Coast out here. The patrolling of these areas would mean a large number of machines, and even then, as the air is so vast, it would still be comparatively easy for the German machines to get to London without having been seen or caught by any of our patrols on the way. This method might, of course, with luck, intercept the machines and either bring them down or drive them back. This has been proved without a doubt during the last two years of fighting on the Western front. The system would, however, lock up a very large number of machines and pilots on a purely defensive plan which would never stop an aggressive enemy.
(b) Another system of patrols would be to patrol over the enemy’s aerodromes to watch for machines leaving. This would also entail a large number of machines and in addition they would either have to patrol under the fire of the enemy’s anti-aircraft guns, or if they kept at such a height that the guns could not do much harm then the aerodrome would very often be out of sight. It would be very hard to know whether our machines were patrolling over the right aerodromes, as during the summer the enemy has many temporary aerodromes, and all our information goes to prove that they move their machines constantly from one aerodrome to another. Temporary aerodromes are made fairly easily during the dry weather.
(c) A third system of patrolling would be to have one or two machines with long-range wireless to patrol the Coast from Dunkirk to Holland watching for the German machine s to come out to sea. This, of course, has the same drawback as the first system of patrolling, i.e. the machine would probably not see the enemy, but, of course, if he did see them and sent his wireless message England would be warned earlier and also Dunkirk, at both of which places a special group of fast machines could be located ready to go up and attempt to follow and attack the raiders. This might be successful at times, but it is not a sure method.
Other methods which have been suggested are:
The constant bombing of German aerodromes. But I would point out that during the whole time we have been on the Western Front only once has a bomb hit one of our hangars, on this occasion it destroyed five machines. We have bombed the enemy’s aerodromes a great number of times, but I do not suppose we have destroyed more than one hundred of his machines in this way, as even if we do hit a shed it is probably a small one containing one machine only, as many German aerodromes have this type of shed.
Daylight bombing from a height is still very inaccurate and though large towns and big stations are easy to hit, it is very hard to hit a small individual shed.
The chief point to remember is that practically none of our machines have got the necessary range or tank capacity for long-distance bombing. It should be remembered that over a year ago we asked that, as soon as the Army had been supplied with the necessary number of machines to enable the Army’s operations to be carried out efficiently, ten bombing squadrons should be provided with a view to carrying out this sort of work. I regret to say we are apparently nowhere near receiving these latter squadrons as we have not yet got the necessary number of machines to meet the needs of the Army.”