At the 1911 meeting of the Institute of International Law in Madrid, legislation was proposed to limit the use of airplanes to reconnaissance missions and banning them from being used as platforms for weapons. This legislation was rooted in a fear that airplanes would be used to attack undefended cities, violating Article 69 of the Den Hague Reglement (the set of international laws governing warfare).
At the start of the war, there was some debate over the usefulness of aircraft in warfare. Many senior officers, in particular, remained sceptical. However the initial campaigns of 1914 proved that cavalry could no longer provide the reconnaissance expected by their generals, in the face of the greatly increased firepower of twentieth century armies, and it was quickly realised that aircraft could at least locate the enemy, even if early air reconnaissance was hampered by the newness of the techniques involved. Early scepticism and low expectations quickly turned to unrealistic demands beyond the capabilities of the primitive aircraft available.
Even so, air reconnaissance played a critical role in the “war of movement” of 1914, especially in helping the Allies halt the German invasion of France. On 22 August 1914, British Captain L.E.O. Charlton and Lieutenant V.H.N. Wadham reported German General Alexander von Kluck’s army was preparing to surround the BEF, contradicting all other intelligence. The British High Command took note of the report and started to withdraw toward Mons, saving the lives of 100,000 soldiers. Later, during the First Battle of the Marne, observation aircraft discovered weak points and exposed flanks in the German lines, allowing the allies to take advantage of them.
In Germany the great successes of the early Zeppelin airships had largely overshadowed the importance of heavier-than-air aircraft. Out of a paper strength of about 230 aircraft belonging to the army in August 1914 only 180 or so were of any use. The French military aviation exercises of 1911, 1912, and 1913 had pioneered cooperation with the cavalry (reconnaissance) and artillery (spotting), but the momentum was if anything slacking.
Great Britain had “started late” and initially relied largely on the French aircraft industry, especially for aircraft engines. The initial British contribution to the total allied airwar effort in August 1914 (of about 184 aircraft) was three squadrons with about 30 serviceable machines. By the end of the war, Great Britain had formed the world’s first air force to be independent of either army or naval control, the Royal Air Force.  The American army and navy air services were far behind; even in 1917, when the United States entered the war, they were to be almost totally dependent on the French and British aircraft industries for combat aircraft.
The Germans’ great air “coup” of 1914 was at the Battle of Tannenberg in East Prussia, where an unexpected Russian attack was reported by Leutnants Canter and Mertens, resulting in the Russians’ being forced to withdraw.
By the end of 1914 the line between the Germans and the Allies stretched from the North Sea to the Alps. The initial “war of movement” largely ceased, and the front became static. Three main functions of short range reconnaissance squadrons had emerged by March 1915.
The first was photographic reconnaissance: building up a complete mosaic map of the enemy trench system. The first air cameras used glass plates. (Kodak cellulose film had been invented, but did not at this stage have sufficient resolution).
Artillery “spotting” enabled the ranging of artillery on targets invisible to the gunners. Radio telephony was not yet practical from an aircraft, so communication was a problem. By March 1915, a two-seater on “artillery observation” duties was typically equipped with a primitive radio transmitter transmitting using Morse code, but had no receiver. The artillery battery signalled to the aircraft by laying strips of white cloth on the ground in prearranged patterns. Observation duties were shared with the tethered balloons, which could communicate directly with their batteries by field telephone, but were far less flexible in locating targets and reporting the fall of shot.
“Contact patrol” work attempted to follow the course of a battle by communicating with advancing infantry while flying over the battlefield. The technology of the period did not permit radio contact, while methods of signalling were necessarily crude, including dropping messages from the aircraft. Soldiers were initially reluctant to reveal their positions to aircraft, as they (the soldiers) found distinguishing between friend and foe problematic.
Reconnaissance flying, like all kinds, was a hazardous business. In April 1917, the worst month for the entire war for the RFC, the average life expectancy of a British pilot on the Western Front was 69 flying hours.
Early bombing efforts
Typical 1914 aircraft could carry only very small bomb loads – the bombs themselves, and their stowage, were still very elementary, and effective bomb sights were still to be developed. Nonetheless the beginnings of strategic and tactical bombing date from the earliest days of the war. Notable are the raids by the RNAS on the German airship sheds at Düsseldorf, Cologne and Friedrichshafen in September, October and November 1914, as well as the formation of the Brieftauben Abteilung Ostende (or “Ostend carrier pigeon detachment”, cover name for the first German strategic bombing unit), which mounted the first token raid over the English Channel in December.
The dawn of air combat
As Dickson had predicted, initially air combat was extremely rare, and definitely subordinate to reconnaissance. There are even stories of the crew of rival reconnaissance aircraft exchanging nothing more belligerent than smiles and waves. This soon progressed to throwing grenades, and other objects – even grappling hooks. The first aircraft brought down by another was an Austrian reconnaissance aircraft rammed on 8 September 1914 by Russian pilot Pyotr Nesterov in Galicia in the Eastern Front. Both planes crashed as the result of the attack killing all occupants. Eventually pilots began firing handheld firearms at enemy aircraft, however pistols were too inaccurate and the single shot rifles too unlikely to score a hit. On October 5, 1914, French pilot Louis Quenault opened fire on a German aircraft with a machine gun for the first time and the era of air combat was under way as more and more aircraft were fitted with machine guns.
Evolution of fighter aircraft
Early attempt on a French Morane-Saulnier L to mount a forward-firing gun
The pusher solution
As early as 1912, designers at the British firm Vickers were experimenting with machine gun carrying aircraft. The first concrete result was the Vickers Experimental Fighting Biplane 1, which featured at the 1913 Aero Show in London. and appeared in developed form as the FB.5 in February 1915. This pioneering fighter, like the Royal Aircraft Factory F.E.2b and the Airco DH.1, was a pusher type. These had the engine and propeller behind the pilot, facing backward, rather than at the front of the aircraft, as in a tractor configuration design. This provided an optimal machine gun position, from which the gun could be fired directly forward without an obstructing propeller, and reloaded and cleared in flight. An important drawback was that pusher designs tended to have an inferior performance to tractor types with the same engine power because of the extra drag created by the struts and rigging necessary to carry the tail unit. The F.E.2d, a more powerful version of the F.E.2b, remained a formidable opponent well into 1917, when pusher fighters were already obsolete. They were simply too slow to catch their quarry.
Diagram of Fokker’s “Stangensteuerung” synchronisation mechanism. Pulling the green handle drops the red cam follower onto the propeller shaft cam wheel. Twice during each rotation of the propeller the cam lifts the follower which depresses the blue rod against the spring, connecting the yellow trigger plate to the purple firing button allowing a round to be fired.
The forward firing gun of a pusher “gun carrier” provided some offensive capability – the mounting of a machine gun firing to the rear from a two-seater tractor aircraft gave defensive capability. There was an obvious need for some means to fire a machine gun forward from a tractor aircraft, especially from one of the small, light, “scout” aircraft, adapted from pre-war racers, that were to perform most air combat duties for the rest of the war. It would seem most natural to place the gun between the pilot and the propeller, firing in the direct line of flight, so that the gun could be aimed by “aiming the aircraft”. It was also important that the breech of the weapon be readily accessible to the pilot, so that he could clear the jams and stoppages to which early machine guns were prone. However, this presented an obvious problem: a percentage of bullets fired “free” through a revolving propeller will strike the blades, with predictable results.
Early experiments with synchronised machine guns had been carried out in several countries before the war. Franz Schneider, then working for Nieuport in France but later working for L.V.G. in Germany, patented a synchronisation gear on 15 July 1913. An early Russian gear was designed by a Lieutenant Poplavko: the Edwards brothers in England designed the first British example, and the Morane-Saulnier company were also working on the problem in 1914. All these early experiments failed to attract official attention, partly due to official inertia and partly due to the terrifying results of failures of these early synchronising gears, which included dangerously ricocheting bullets as well as disintegrating propellers.
The Lewis gun, used on many early Allied aircraft, proved next to impossible to successfully synchronise due to its open bolt firing cycle. In an open bolt firing cycle, it is impossible to predict the exact time any given round will fire, a problematic characteristic in a weapon one is attempting to fire between the spinning blades of a propeller. Photographs of fuselage-mounted Lewis guns aimed directly ahead on RNAS aircraft, and looking as if they “should” be synchronised — as with some of their Bristol Scouts — were probably in fact free firing, hardly a satisfactory solution.
A Morane-Saulnier’s propeller with the “wedges” fitted.
The Maxim guns used by both the Allies (as the Vickers) and Germany (as the Parabellum MG 14 and lMG 08 Spandau) had a closed bolt firing cycle that started with a bullet already in the breech and the breech closed, so the firing of the bullet was the next step in the cycle. This meant that the exact instant the round would be fired could be predicted, making these weapons considerably easier to synchronise.
The standard French light machine gun, the Hotchkiss, was also most unamenable to synchronisation due to rounds “hanging fire”. The Morane-Saulnier company designed a “safety backup” in the form of “deflector blades” (metal wedges), complete with metal tiebars extending outwards from the propeller hub for bracing, fitted to the rear surfaces of a propeller at the radial point where they would be struck by a bullet. Roland Garros tried out this system in a Morane-Saulnier L in April 1915. He managed to score several kills, although it proved to be an inadequate and dangerous solution. Garros eventually was forced by engine failure (possibly caused by the repeated strain on his aircraft’s crankshaft of the “deflected” bullets striking his propeller) to land behind enemy lines, and he and his secret weapon were captured by the Germans.
Famously, the German High Command passed Garros’ captured Morane to the Fokker company – who already produced Morane type monoplanes for the German Air Service – with orders to copy the design. The deflector system was totally unsuitable for the steel-jacketed German ammunition so that the Fokker engineers were forced to revisit the synchronisation idea (perhaps infringing Schneider’s patent) resulting in the Eindecker fighter series. Crude as these little monoplanes were, they produced a period of German air superiority, known as the “Fokker Scourge” by the Allies. The psychological effect exceeded the material – the Allies had up to now been more or less unchallenged in the air, and the vulnerability of their older reconnaissance aircraft, especially the British B.E.2 and French Farman pushers, came as a very nasty shock.
The actual Scout C, RFC serial no. 1611, flown by Lanoe Hawker on 25 July 1915 in his Victoria Cross-earning engagement.
Another method used at this time to fire a machine gun forward from a tractor design was to mount the gun to fire above the propeller arc. This required the gun to be mounted on the top wing of biplanes and be mounted on complicated drag-inducing structures in monoplanes. Reaching the gun so that drums or belts could be changed, or jams cleared, presented problems even when the gun could be mounted relatively close to the pilot. Eventually the excellent Foster mounting became more or less the standard way of mounting a Lewis gun in this position in the R.F.C.: this allowed the gun to slide backward for drum changing, and also to be fired at an upward angle, a very effective way of attacking an enemy from the “blind spot” under its tail. This type of mounting was still only possible for a biplane with a top wing positioned near the apex of the propeller’s arc – it put considerable strain on the fragile wing structures of the period, and it was less rigid than a gun mounting on the fuselage, producing a greater “scatter” of bullets, especially at anything but very short range.
The earliest versions of the Bristol Scout to see aerial combat duty in 1915, the Scout C, had Lewis gun mounts in RNAS service that sometimes were elevated above the propeller arc, and sometimes (in an apparently reckless manner) firing directly through the propeller arc without synchronisation. During the spring and summer of 1915, Captain Lanoe Hawker of the Royal Flying Corps, however, had mounted his Lewis gun just forward of the cockpit to fire forwards and outwards, on the left side of his aircraft’s fuselage at about a 30° horizontal angle. On 25 July 1915 Captain Hawker flew his Scout C, bearing RFC serial number 1611 against several two-seat German observation aircraft of the Fliegertruppe, and managed to defeat three of them in aerial engagements to earn the first Victoria Cross awarded to a British aviator.