Air Defence on Outbreak of War

The threat of warfare from the air was recognised when the development of aeroplanes and airships began. The Hague Conference of 1899 signed a declaration which banned the dropping of “projectiles or explosives from balloon or other aerial vessels”.


In Britain the threat from the air was taken seriously as it provided a means of bypassing the sea barriers that had protected her for centuries.  The problem was how to meet this threat – by fire from the ground or from the air? The majority opinion of the time was that the threat would be best met with guns mounted in defending airships or aeroplanes because:

  • Airships and aeroplanes would be challenging targets to hit with ground fire

  • Effective defence would require an impracticable number of guns and crews to be maintained all over the country.


The Navy in particular was aware of the threat from the air to its naval bases. In 1910, the Home Ports Committee composed of Admiralty and War Office members laid down some principles for air defence which actually remained in relevant for many years. They decide that:

  • No form of fixed defences (armaments), mobile defences (guns mounted on lorries) or passive defence (overhead cover) would ever be sufficient to meet aerial attacks.

  • The most effective form of meeting aerial attack would be with airships or aeroplanes, working in cooperation with fixed defences of a special nature (a recognition of the need to provide searchlights).

  • The constructing of important magazines should be underground or if this was impracticable they should be dispersed.


Germany was also well aware of the potential of aerial warfare.  Thinking of the time is reflected in a lecture given by Kapitan Von Pustau of the Imperial Navy in late 1911: “Let us imagine a war with England, England from which time immemorial has had an unwarlike population .... If we could only succeed in throwing some bombs on to their docks, they would speak with us in quite different terms. With airships we have in certain circumstances the means of carrying the war into the British country, and in England one imagines with terror that one can already hear the beating of the screws of the Zeppelin cruisers”.  


In 1912, Britain took the first steps to meet such a threat, with the formation of the Royal Flying Corps, along with a Naval Wing, in which flights were organised by the Royal Navy for the defence of ports and shipyards.  The formation of the RFC was along the lines laid out by an Imperial Defence Committee sub-committee which was formed in November 1911 and their report formerly adopted in April 1912. The RFC consisted of:

  • Central Flying School

  • Naval Wing

  • Military Wing

  • Reserve


Aircraft and airships took part in the large scale September 1912 Manoeuvres, where General Haig’s Red Force played the role of an  invading force, landing in East Anglia and advancing on London while General Grierson commanded the defending force Blue Force.  Although early days in the military use of aircraft and airships, Grierson and the Manoeuvres Director, Sir John French, recognised the potential.


By 1914 the Military Wing had formed five squadrons out of a planned seven while the  Naval Wing had established six seaplane stations along the coast with more planned.   A list of aeroplanes in private hands had also been drawn up which could be used in times of war and arrangements made for the RFC to use four private aerodromes. The fist experiments with guns mounted in aircraft and the dropping of bombs from aircraft had also been undertaken.


A Central Flying School had been established at Salisbury Plain and the recognition of the desirability of establishing a second near the coast where training could be carried out in alighting on and rising from land or water. Topics taught included flying, mechanics, navigation and steering by compass, meteorology, observation,  signalling and warship recognition.  A naval wireless set had also been placed in a Maurice Farman machine with promising results.  The Military Wing had also had success with wireless and it was now possible to transmit and receive messages in full flight (although it would not be until 1918 that fighters defending London were fitted with wireless sets).  The Naval Wing had a flying school at Eastchurch and also established an experimental station at Isle of Grain.  


Much work had been undertaken in the development of seaplanes by the Naval Wing.  HMS “Hermes” was commissioned in the summer of 1913 and specially fitted to carry seaplanes. She had a launching platform and the quarter deck was cleared of guns etc to provide accommodation for seaplanes. During 1912, the Army Council had ordered the experimentation with hydro-aeroplanes for coast defence. Envisaged roles were directing fire from coast batteries against hostile ships and to attack hostile aeroplanes.  It was offered to turn this experimental work over to the Admiralty but the Navy stated they had no need for a F.E.-2 type that the Army was experimenting with. This state of affairs led to concern as to who would be responsible for coast defence by aircraft, which would not be settled until October 1914 with the formation of the Royal Naval Air Service which assumed responsibility for the entire country against air attack.


The development of the Zeppelins resulted in the urgent need to develop guns for use against aircraft, as it was recognised that Zeppelins could cross the North Sea and attack Britain with bombs.  The first anti-aircraft guns, 6” howitzers, were mounted at Chattenden and Lodge Hill Magazines in 1913 as a temporary measure until new guns suitable for aerial work were ready for use.  Guns under manufacture for aerial work were:

  • 4 inch Q.F.

  • 12 pdr Q.F.

  • 3 inch Q.F.

  • 1 pdr Q.F.

  • 37 mm pom-poms

  • 18 pdr field guns


On the outbreak of war, almost the entire R.F.C. was dispatched to France, a situation foreseen by the First Lord of the Admiralty, Winston Churchill.   With virtually no anti-aircraft guns sited in Britain as well, no effective air defence existed during the first year of the war.  


Churchill outlined the policy for the defence of Britain on 9th September 1914. He recognised that it would be impossible to defend London, or any other city, with artillery alone. Guns were to be limited to sites of military value, with searchlights in order to either expose the enemy to the risk of gunfire or force him to fly so high that accurate bombing was not possible.  An intercepting force of aircraft was to be maintained within range of a line drawn from Dover to London. A squadron of aircraft was also to be maintained at Hendon to intercept any enemy aircraft that may try and attack London.  Just as important was the requirement to maintain a strong force overseas to deny the French and Belgium coasts to enemy aircraft and to take every opportunity to bomb Zeppelin bases. London and other cities were to darken their streets at night and people advised to seek cover while a raid was in place. The coastal towns were virtually undefended at the start of the war, as they lacked obvious targets of military value; there may also have been a hope that Germany would not bomb civilian targets.


In October 1914 the newly designated Royal Naval Air Service (R.N.A.S) assumed responsibility for the entire country against air attack. Luckily for Britain, Germany was not ready to commence aerial warfare following some serious setbacks with Zeppelins and at first a reluctance to target England.  This allowed time to begin to assemble defences to meet the threat.  Britain did not learn this lesson and found itself in a similar situation as the Second War loomed, Dr MacDougall recently noting that the Phoney Peace and Phoney War gave Britain the vital time required to begin assembling the defences.


The R.F.C. also took some measures to defend London with its few aircraft remaining in Britain. In October 1914, instructions were given to maintain two B.E.’s with grapnels or bomb-boxes at Hounslow and two Henri Farman machines at night at Joyce Green. The Henri Farman’s were to fly with a mechanic as a passenger equipped with rifles, grenades, flaring bullets with Martini carbines and a few hand grenades with rope tails.


The Admiralty also organised some form of anti-aircraft defence for London, the Army resources being fully stretched by maintaining the Field Army at the Front. The defence was organised by the R.N.A.S. with personnel largely from the R.N.V.R. They were armed with four six pounder Hotchkiss guns and six 1 ½ pdr  Pom-Poms, with a few acetylene searchlights to work with the guns. In addition, there were two 3” guns manned by the Royal Marine Pensioners in fixed emplacements at Tower Bridge and Green Park. Other guns were located at other military targets such as Chatham, Dover, Portsmouth and Harwich.


The war was also taken to the enemy, with Zeppelin Z.9 destroyed in her shed at Dusseldorf and another raid on the sheds at Friedrichshaften damaged another.


As early as September 1914, the German Naval Staff and Imperial Naval Board had discussed the question as to whether airships should be used against England. Due to the small number of airships then available, and their importance for naval reconnaissance, it was decided to wait until a sufficient reserve existed for both uses.  The German High Command considered the best way to use the Zeppelins against London was in flights of 20 each carrying 300 incendiary bombs. Such a load would be able to start at least 1,000 separate fires which would overwhelm London’s fire brigades. The requisite number were available by December, Further complications caused delay in granting permission to use airships against England. Firstly, it was initially envisaged to use the whole of the aerial forces available, in a combined attack with the Army airships. However the Army first wanted to use its Z airships in attacks against the French fortified towns of Nancy, Dunkirk and Verdun. Secondly, the Imperial Chancellor was anxious that London should not be included as a target in any raids on England.


The Chief of the Naval Staff considered London to be a justifiable target, due to its important military establishments on the Lower Thames. He also considered any further delay could result in further British air raids on Zeppelins in their sheds, putting them out of action before they took part in operations against England. The Chief of the Naval Staff justified London as a legitimate target in the following memo, dated 7th Jan 1915:


“London must be regarded as a defended area in the sense of the Hague Convention because mines are laid in front of the port, precautionary measures for anti-aircraft defence taken by placing guns in position, and because the land fortified to the south of the city which consist of three forts and 10 redoubts and come within 12 kilometres of the city itself, together with the fort on the north front, must be regarded as direct defences of London.


In addition, London contains highly important military establishments, including the Admiralty premises from which the movements of the fleet are controlled by wireless, also barracks, munitions depots, oil tanks, wharves, docks etc.


I hold the view that we should leave no means untried to crush England and that successful air raids on London, in view of the already existing nervousness of the people, would prove a valuable means to this end”.


Permission was finally given for the proposed raids on England, but the Kaiser insisted they be limited to military targets and that London was not to be bombed.  When attacks were eventually authorised against London, he still forbade attacks on Buckingham Palace, Westminster Abbey and St Paul’s. The idea of cooperation with the Army had to be given up, as it would have resulted in further delays and weather conditions on the Coast and the interior would have made a simultaneous advance seldom possible. The first raids were launched on the night of 19th / 20th Jan.