Man has pondered about flying for as long as we have records. We have the story of Icarus, in Greek mythology, for example, dating back to the B.C years. We have the early sketches of Da Vinci's flying machines, ingenious designs originating from the anatomy of birds, becoming more complex as practicality dictated that a man just did not have the power to flap mechanical wings to maintain lift.
In 1906, the first unaided takeoff is conducted, by the Brazilian Santos-Dumont, aboard his 14 Bis (Oiseau de proie, in french). With planes that could now fly without needing help to takeoff, the military quickly started to invest in the new technology.
In World War I, we see the first use of actual airplanes in battles, rather than scouting balloons. These primitive planes lacked great firepower, being equipped only with a machine gun, and a few bombs. Well....the bombs weren't exactly equipped to the planes, to be honest.pilots would carry their very small bombload, and drop them like grenades from the plane. In spite of its primitiveness, this was the first instance of aerial strategic bombings.
Their roles were primarily reconnaissance, but they saw more combat as the war went on. These early planes gave rise to the famous Ace pilots, who would engage in dogfights to try to take down another nation's planes. The most effective and well known ace was the German pilot Manfred von Richthofen, better known as the Red Baron. He was so dominant in his time period (8 more confirmed takedowns than the British Ace, 56 more than the American Ace) that most people today still know him, for some reason or another. Interestingly enough, there is a frozen pizza brand named after, and the letters used to write Red Baron can be reorganised to write Bernardo, likely the coolest anagram of my name..
Airplanes would eventually become much more sophisticated, and would become an essential characteristic of the, then, warfare of the future.