Dragons, or wyverns, are of course creatures that fly, that are fierce and can participate in dogfights against other dragons. I wouldn't be surprised if in a fantasy world humans domesticated dragons to use as early "airplanes".
So in a scenario I have in mind dragons have been used by few western countries as "airplanes" in their army. They have a special scarf that determined what country it fought for (for instance a blue, white and red scarf would mostly be French, add a yellow color and you will have the one of the Russian Empire, black and white would point at the Prussians and black, white and red the German Empire etc.).
But then the 20th century comes... and WW1... and guess what we have during WW1? The first main usage of airplanes in war.
However in WW1, airplanes were a tad simpler, being a bunch of fiber, sticks, bars and equipment carefully assembled to create a suitable flying machine. Sometimes I heard that the pilot even should pull out his own gun and shoot at the other airplanes. Also WW1 era airplanes are slow (compared to modern aircraft).
Which begs me the question:
Can dragons at least survive if they were chased and caught in a dogfight by a WW1 mono/bi/triplane? Would that be even fair in the first place?