<P> While the impact of aircraft on the course of the war was mainly tactical rather than strategic, most important being direct cooperation with ground forces (especially ranging and correcting artillery fire), the first steps in the strategic roles of aircraft in future wars was also foreshadowed . </P> <P> 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). </P> <P> 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 skepticism and low expectations quickly turned to unrealistic demands beyond the capabilities of the primitive aircraft available . </P> <P> 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 . </P>

When were planes first used in world war 1