Political event
Worldwide, the Elven population disappear, almost overnight. Mass chaos erupts, as the upper-most levels of all governments quickly vanish, leaving a panicked number of slave races scrambling to fortify their own power in the vacuum.
The Elves had ruled for as long as any race could remember, and now they were gone. Fled, practically overnight, an entire worldwide empire gone in hours. There's no explanation for how it happened, or even why. The elves refuse to talk about it, and often even asking is considered an insult. Governments, administrative bodies, all collapsed immediately, plunging the world into chaos. Some elves chose to remain, or were considered of low enough importance to be left behind. If any were aware of the reasons why, they too, are not speaking. In the aftermath, individual leaders of different races and factions started jockeying amongst each other for power. Alliances were made, treaties drawn up, skirmishes, attacks, and soon military action started to escalate.