Ahn'Qiraj Remembrance Day is a micro-holiday coming with Patch 7.1.5. It is a one-day event that takes place every January 22nd, the same day in 2006 that the Gates of Ahn'Qiraj were opened for the first time in Silithus.
On this day, players may travel to Silithus to take part with their faction, gathering fragments for turn-in.
At the end of the event, the winning faction will have their banner placed atop the walls of Ahn'Qiraj, where it will remain until the Remembrance Day rolls around again the following year. There are no buffs or achievements associated with the event.