Winter: yes! These dragons were facing extinction.
Summer: the first event that started the war was they rounded up as many of these dragons as they could. Since they were curious because many of them have never even seen a human before, they went willingly. As soon as they were gathered, they opened fire using everything from conventional bullets to experimental weapons, around a million dragons died, and the only reason we know that is someone was able to recover records from one of the complexes they took over. I just spoke with one of the dragons.