The Emerald Warden was a longlasting sub-clan underneath the Origo Rebellion, independent in leadership and operations. 
Emerald warden flag

The flag of the Emerald Warden as of 690 A.P

The emerald wardens was founded by Altoriss Fanagan, a former high ranked soldier in the Cortus Monarchy. Upon hearing of the deeds of the Origo rebellion, he immediatly took off with his most loyal soldiers and established the first division within the rebellion. 

The Emerald Warden would survive the death of the rebellion in 715 A.P and continue as an independent faction for the time to come. By the time the union war began, the Emerald Warden would immediatly merge with the rebels of Vastus and found the Ardent Union.