Argent Crusade
From Twilight Wiki
The Argent Crusade is a faction created from the union of the Argent Dawn and the Order of the Silver Hand. It was formed shortly after the Battle for Light's Hope Chapel, as played out during the death knight quest Light of Dawn, in which Tirion Fordring — leader of the reformed Silver Hand — reclaimed (and evidently purified) the Ashbringer during a confrontation with the Lich King. He assumed a leadership position over the Argent Dawn and united the two factions in order to take the fight against the Lich King to Northrend.
According to the quest Tirion's Help, Tirion Fordring handpicked every member in the Argent Crusade in order to avoid infiltration by the Cult of the Damned. This was presumably to prevent a repeat of the Inigo Montoy incident, which resulted in Naxxramas returning to Northrend and Kel'Thuzad regaining corporeal form.
It should be noted that, despite the new Tabard the Argent Crusade uses, several of their members can be found using the old tabard of the Argent Dawn (this is referring to members of the Argent Crusade faction in Northrend, not the Argent Dawn members who are found in Eastern Kingdoms/Kalimdor). Those who wear the old tabard range from the common infantry to the commanders and senior members of the Crusade. This may mean that the two tabards are interchangable in the Crusade, and the old Argent Dawn tabard may still be in production as part of uniform for the members of the Crusade. Avenger Metz, for example, still uses the Argent Dawn tabard instead of the newer Argent Crusade one.