Centuries ago, shortly after the Searing and the exodus led by Prince Rurik, a group of soldiers chosen by King Adelbern I went behind enemy lines to strike at the charr from within their own territory, while stationed at the now-abandoned Eye of the North, in norn lands. The group eventually grew after succeeding in the rescue of several prisoners held by the charr, and the group adopted the name Ebon Vanguard, which is still used nowadays.
Years later, when the peace treaty between human and charr was to come into effect, the Ebon Vanguard was recalled back to Ascalon, and integrated the Ascalonian Army as their elite force.
The best men in the Ascalonian Army all have a chance of being invited into this force, though there’s still tests they must go through in order to integrate it. These aren’t, by any means, easy, which results in a large failure rate for potential new members.
Due to their status and history, it’s not unusual for allied nations to enlist the help of the Ebon Vanguard. Ascalon’s support helps reassuring the status of their many alliances, as well as the strength of their military.