I wonder if Future Lucy or the princess is not spinning things a little. Was it an army of dragons, or was it just one dragon, ACNOLOGIA .
It's possible that the reason why the Dragon Army came might have been twisted. We know that Igneel and other FT DS's Dragons will come (Igneel himself mentions it at one point in the story) and it would be strange for them to suddenly have the desire to destroy humanity (they did take care of human children). This could mean that they didn't came to destroy humanity, but perhaps to destroy the Dragon Slaying Dragon King Acnologia (and we know that Acnologia is the one that brings an end to civilizations).
Originally Posted by paulbee