You probably think that the first airplanes that were used in combat were in WWI. But if you did think that, you’d be wrong.
In 1912, Serbia, Montenegro, Bulgaria and Greece got together and created what was known as the Balkan League. From October of 1912 to May 1913, the armies of the Balkan League pushed the Ottomans out of most of Europe. This is known as the first Balkan War, and it was this war that first saw the use of airplanes in a military function in Europe.
On October 16th, 1912, observer Prodan Torakchiev, dropped two bombs on a Turkish railway station. He dropped these two grenades from an albatross F2, which was a German-produced plane that was being piloted by Radul Milkov.
This actually wasn’t the first use of airplanes in warfare outright; that actually took place about a year earlier when an Italian pilot dropped some grenades on a Turkish position in Libya. But because of this bombing, October 16th to this day is Bulgaria’s Air Force Day.