You can now declare your surrender within the first 24 to 25 hours after a war declaration. CITY DECLARE SURRENDER TO <organization> is the command. Doing so will give up your territories and place you into a state of surrender for 25 IRL days.

HELP WAR has reference to this command if you need it.

Penned by my hand on Kinsday, the 12th of Haernos, in the year 0 AC.