Ponies & Paragons
For many years, Princesses Celestia and Luna worked towards having the Castle of the Two Sisters rebuilt and reconfigured into a new castle for Princess Twilight Sparkle. When it was finally completed, about twenty years after Twilight’s coronation, all four princesses held a celebratory unveiling event.
Many unicorn wizards were charged with casting a magical shield to keep the Everfree Forest at bay while the newly christened Everfree Castle was revealed to the public.
However, while the shield did quite a good job at keeping the forest at bay, that is all it kept out. With all four princesses in one place, and the royal guard defending the city of Canterlot, there was virtually no resistance when a dragon raiding party infiltrated the event in an attempt to kidnap the princesses.
With the help of the wizards and Shining Armor, both Princess Twilight Sparkle and Princess Cadence escaped. However, Celestia and Luna were both captured with antimagic restraints and taken to the Land of Dragons as prisoners.
This event marked the escalation of hostilities with the dragons and, upon learning that the abduction was ordered by the dragon emperor, lead to the beginning of the Great Dragon War.