The FFXI team has put out some new info on the upcoming expansion. This time around they have updated the official site with an introduction to the battle event "Besieged". Check it out at the read link below.

“Besieged” is a form of defensive battle that takes place when enemy forces breach the gates of Al Zahbi. The Imperial army declares martial law, and the city is enveloped in conflict.

After martial law is declared, anyone in the area who can use a weapon is required to join the Imperial Army in combat and take charge of Al Zahbi's defense. However, repeated beastman attacks have nearly destroyed the city's fortifications, transforming the majority of these defensive battles into aggressive clashes on the streets themselves.  
 
Al Zahbi's enemies are after one thing--the “Astral Candescence” located in the Hall of Binding. The fate of Aht Urhgan and the beastmen ride on this single item, which allegedly draws upon the infinite energy of the Astral Plane.

Five “Serpent Generals” hold the keys to the Hall of Binding. They must be protected at all costs while driving the beastmen from the city. The safety of the townspeople and the future of Al Zahbi rest in the hands of the adventurers!