The British and the Allies were the first to employ airplanes in combat during WWI. Airplanes were especially useful in providing reconnaissance. Information obtained from early flights provided intelligence that enabled the Allies to stop the German invasion of France.
Prior to the war, many military officials were skeptical about the usefulness of airplanes in combat, though opinions quickly changed. In addition to reconnaissance, these early airplanes were outfitted with machine guns and small bombs, and were sometimes used to deliver chemical weapons. The German's relied heavily on Zeppelin airships for aerial reconnaissance and bombing runs. Developments made in World War I were crucial to the advancement of aviation.