The First World War, although not quite the first conflict to involve the use of air power (that occurred a couple of years earlier), was certainly the first big one.
One does recall Blackadder and the Twenty-Minuters at this point (Blackadder Goes Forth is a brilliant series), but there were elements to this. For a start, pilots didn't have parachutes and there were no ejector seats.
Most of the inherent concepts of air combat were initially drawn up in that war- the Dicta Boelcke, for example.
The Air War saw German Zeppelins bombing London and other cities in the UK- civilians were no longer safe just be being far away from the front-line. An impact of this that none of us like.