It's an in-game event that lasts for 7 days, during which several guilds fight each other over towns. The more towns you have, the more resources you gain and more powerful you become. During first day, strong guilds take 10-20 towns each, then on the second day, they fight each other for the towns each got.
My guild is one of the strongest, we got more than 20 actually, but then on the second day, guild we had NAP with attacked us from the back, took several towns, and it led to chain effect (as we ran out of resources) and we lost all towns.