Aircraft technology was little over a decade old when Archduke Franz Ferdinand's assassination in late June 1914 ultimately resulted in the outbreak of 'The Great War' a month later.
Initially deemed of little use to the armed services other than in a reconnaissance role, aircraft development exploded during wartime (all too often literally). When war broke out the number of aircraft on all sides and all fronts was very small. The period between 1914 and 1918 saw not only tremendous production, but also tremendous development in aircraft technology. In 1914 it was important that aircraft be easy to fly, as the amount of training that pilots received was minimal, to say the least. Not only did aircraft become faster, more manoeuvrable and more powerful, but a number of technologies that were common at the start of the war had almost disappeared by the end of it. Many of the aircraft in 1914 were of "pusher" layout. This is the same configuration that the Wright brothers used, where the propeller faced backwards and pushed the aircraft forward.
The alternative layout, where the propeller faces forwards and pulls the aircraft, was called a "tractor" design. It provided better performance, but in 1914 visibility was deemed more important than speed. World War One marked the end of pusher aircraft.