to the Straits of Tsushima or to Sedan," which leads up to the

statement :

Fighting in the air can never be an end in itself: it is never more than a means to an end. Since we can, we therefore must proceed direct towards this end, namely, the attack of the enemy vital centres, whatever those centres may be.

"Statesmen and citizens," for whose military education" The Study of War" has been compiled, will be grateful to Air ViceMarshal Brooke-Popham for his very clear exposition of the doctrine of war which derives from the teaching on principles at the Royal Air Force Staff College, and is held by the authorities of the Royal Air Force. They cannot fail to observe, however, that it is a doctrine which differs fundamentally from that held in common by the navy and the army. Before they resign themselves to accepting as a fact the permanence of a cleavage of thought on war between the services, with all the dangers of friction at the top which such cleavage entails, they would do well to examine for themselves the soundness of the arguments advanced to justify a separate air force doctrine of war and the expediency of admitting that doctrine.

To take the last point first. Is it expedient for this country to proclaim that "attacks may be made on large towns with the deliberate object of terrorising the inhabitants ? " Air ViceMarshal Brooke-Popham admits that "this method is attended by certain disadvantages of which the ultimate moral effect on the attacking nation is itself not the least." His fellow lecturer before the University of London, Admiral Richmond, dots the "i's" and crosses the "t's" of this discreet and half-hearted modification of the doctrine of " frightfulness" when he reminds us that neutrals have both rights and feelings. Admiral Richmond tells us :

To form plans for war which exclude consideration of the neutral, is the height of folly. The German did it on land and sea. His violations of neutral rights were the direct causes of adding Great Britain, Italy, and the United States to his list of enemies. And in this connection, I would point out-though it may be a digressionthat there is already a tendency to forget this lesson. We hear of airbombing and poison-gas attack upon civil populations. It is true that neutrals, for a long time, took no active steps to prevent the murder of their nationals at sea, but in the end the most powerful neutral intervened. Similarly, neutrals may, and should, have something to

say if their people in foreign cities, and particularly their diplomatic and official representatives are the victims of poison-gas bombs dropped in the neighbourhood of, say, the Albert Gate or the Via Vente Settembre. Moreover, such action leads invariably to retaliatory action, and the retaliatory power possessed by a fleet is very considerable in certain circumstances. Once retaliation is provoked, and begun, the Aristotelian object of war-a good peace becomes unlikely of fulfilment.

It is important that Admiral Richmond has nailed to the counter the loose talk on the question of "frightfulness expedient method of war, which has been only too prevalent in recent years and is crystallized in Air Vice-Marshal BrookePopham's statement that "attack may be made on large towns with the deliberate object of terrorising the inhabitants." One seems to recollect that the present Chancellor of the Exchequer, when he was First Lord of the Admiralty, branded the officers of the Imperial German Navy as "baby killers," because of a little incident at Scarborough, which must seem trifling to any one who appreciates the full import of the suggestion contained in Air Vice-Marshal Brooke-Popham's lecture. In war, terrible things have been done, and done justifiably, as reprisals for warcrimes committed by an enemy. One is inclined to speculate what measure of reprisal our next enemy would feel entitled to take against our prisoners of war and interned civilians, if the British Government of the day mustered up sufficient contempt for the good opinion of civilised neutrals-and for the historic past of this country-to initiate decisive operations of the type we have been considering.

It is, however, an idle speculation. Except possibly by way of reprisals, it is difficult to imagine any British Government sanctioning a deliberate attack by terrorisation on the non-combatant men, women and children of the enemy country. In plain English, all this talk of decisive attack by air on the morale of the enemy civil population in order to frighten its government into making peace is just mere idle talk, and putting it into a lecture to the University of London does not make it any less so. This is still a civilized country and it is also a sensible one. It remembers that Germany was deprived of submarines and aeroplanes by the Treaty of Versailles because she had put both those weapons of legitimate warfare to illegitimate uses. Any British Government would have a short shrift which put into the hands

of an enemy so potent an instrument of anti-British propaganda as the initiation of "frightfulness" in air warfare. One lesson of the last war was the potency of propaganda. Another was that propaganda to be effective had to be based on truth. Our propaganda was most effective because our foolish enemy violated the ancient and honoured customs of war and the provisions of international law, and so gave us wonderful cards to play. Are we going to imitate his folly?

The only possible conclusion is that decisive air attack by terrorisation on the morale of our enemy's civil population is not an operation of British warfare.

If terrorisation be ruled out, there remain for consideration two points which are essential to an air force doctrine of war, distinct from and incompatible with that held by the navy and army, viz., the attainment of victory by decisive air "attack of the enemy's vital centres, whatever those centres may be," and the possibility of carrying out such operations without obtaining air superiority by fighting and beating the air forces of the enemy. The vital centres in question are defined by Air Vice-Marshal Brooke-Popham as being the centre of government, and the centres of transportation, supply, water or lighting systems, the attack on which is to be of such a character as to "bring about a continued dislocation of the normal life" of the enemy people. To these targets, with an importance mainly psychological, can be added, of course, a long list of targets of more purely military importance, such as docks, munition works, aerodromes, etc., which are normal targets for naval or military artillery or of air forces co-operating with and forming part of a fleet or army engaged in the operations of war.

It is, however, the psychological targets, the attack on which is to bring about a continued dislocation of the national life, with which we are now concerned. The first point which stands out is that attacks of this type, designed to bring about such a dislocation of the national life as will have a decisive effect on the war by breaking the enemy's will to fight and compelling him to make peace on our terms, must be sustained attacks; they cannot be mere raids with intervals between them, which allow the enemy to make good the damage done. We are considering what is, in fact, a major operation of war-decisive air attack, resolutely maintained until the object of the operation is attained. The

object to be attained lies in the unmapped field of national psychology, since it involves using pressure on the enemy people to force their own government to make peace on our terms. Such direct pressure on an enemy people, and by them on their government, as is involved in the hardship consequent on blockade is, as Admiral Richmond has pointed out, the method of sea-power after the enemy fleet has been destroyed or neutralised. It is the prospect of it, in the form of occupation of territory, which leads to peace on the victor's terms in war on land after the hostile army has been defeated decisively in battle.

The fact that navies and armies have to destroy or neutralise the enemy's navy or army before applying psychological pressure on the enemy country by blockade or by occupation, in itself preserves their home country from the possibility of the enemy applying to it similar psychological pressure by counter-occupation or counter-blockade assuming that the latter is of legitimate character and not the illegal submarine warfare which brought America in against Germany. On the other hand, if Air ViceMarshal Brooke-Popham is right in his contention that air attack can indeed attain its objectives without overcoming the resistance of the defender's air forces, there seems to be no reason why the defender should not apply to his adversary precisely the same psychological pressure by bombing similar targets, successful attack on which will " bring about a continued dislocation of the normal life." It then becomes a question which nation will stand such attack longest : victory will go automatically to the one whose civil population has the better nerves, or, having a less highly organized national life, can best stand interruption of its essential services. War, in short, becomes a gamble on the unknown and un-appraiseable psychological value of nations.

In his introductory lecture on "The Study of War," Sir George Aston discusses the question whether war is an art, a science, or a business competition. Air Vice-Marshal BrookePopham provides a fourth alternative: that it is a game of chance, a mutual bombing the results of which no one can foretell. Before resigning ourselves to the implications contained in accepting this novel conception of war it is as well to examine the foundation on which it rests, viz., that air attacks can attain their objective without overcoming the defender's air forces.

In support of this contention, Air Vice-Marshal Brooke

Popham adduces certain technical considerations, of which the most important is the limited air endurance of fighting aircraft at the present stage of their development. This precludes the defender from maintaining a barrage of fighting machines in the air, while machines sent up to engage an attacker, whose rapid approach has been reported, will probably be too late to engage their adversaries before the target has been bombed. Further difficulties in the way of the defender are that attacks may come from any direction, and that aeroplanes in the air are frequently not seen by the pilots of other aeroplanes. It should be admitted at once that the experience of the late war fully bears out this contention. But, and this is a very important point, we must add that this experience was limited to air raids: we have to guide us no war experience whatever of sustained air attack of a character so decisive as to be a major operation of war. It is the possibilities and limitations of that type of attack that we are now examining.

The three services are at one on the subject of raids. Raiders, whether at sea, on land or in the air, operate by evasion and surprise. Command of the sea has never given British commerce immunity from attack by raiders, either in the late war or in previous wars at sea, while on land the raids of Stewart, Sheridan and de Wet show what can be done by boldly-handled bodies of mounted men, which can evade successfully the area occupied by an enemy's fighting forces. In the late war, surprise enabled trench raids, which evaded the defender's artillery barrage, to be of almost daily occurrence at some point or other of the long trench lines; while our experience of German air raids confirms Air Vice-Marshal Brooke-Popham's contention that in three dimensional space the odds are on the raider and against the defender.

From its very character, however, a sustained attack, intended to produce decisive results on the course of the war, whether carried out by a fleet, an army or an air force, enjoys none of the advantages inherent in a raid. In its inception it may, and if possible it should, come as a surprise; but the course of the operation itself will disclose its character, thus enabling the enemy to offer what resistance he can, unless he resigns himself-which is improbable to allowing a major operation to attain its decisive end unopposed. As soon as a sustained attack, by being pressed