Some history on The Grey Wardens.

"In war, victory.

In peace, vigilance.

In death, sacrifice."

-- Grey Warden motto

The Grey Wardens are an ancient organization of warriors of exceptional ability dedicated to fighting darkspawn in all of Thedas.  They are headquartered in the very place of their founding, the Weisshaupt Fortress in the Anderfels, but maintain a presence in most other nations as well.  The Grey Wardens are known for ignoring a recruit's racial, social, national, and even criminal background if they deem the person valuable in terms of character of ability.

Despite their small numbers, the Grey Wardens have been instrumental in defeating each Blight so far, and thus are vital to the survival of the world as a whole.

History

The first Blight had already raged for 90 years.  The world was in chaos.  At Weisshaupt fortress in the desolate Anderfels, a meeting transpired.  Soldiers of the Imperium, seasoned veterans who had known nothing their entire lifetimes except hopeless war, came together.  When they left Weisshaupt, they had renounced their oaths to the Imperium.  They were soldiers no longer: They were the Grey Wardens.

The First Blight & the Founding

The First Blight occured in -395 Ancient (395 years before the Chantry calendar), or 800 TE (800 years from the founding of the Tevinter Imperium), a plague was unleashed upon the world.  The Deep Roads, underground highways built by dwarves, were swarmed with monstrous creatures that became known as the "darkspawn".  These creatures seemed limitless in number, and spread a taint that infected other living creatures, mutating them into monsters, and corrupted and poisoned the very environment around them.  The cult of the Maker claimed this was the result of Tevinter mages entering the Fade through a ritual and attempting to usurp the Gold City, although dwarves and other non-humans discounted the theory.  Nevertheless, this invasion of darkspawn -- named the Blight -- soon destroyed most of the underground kingdoms of the dwarves and spread to the surface world.  Thedas was in chaos and entered a dark age.  The darkspawn were found to be led by an immensely powerful dragon tainted with the darkspawn corruption; this creature was named an archdemon and believed to be one of the Old Gods worshipped by Tevinter.

In -305 Ancient (890 TE), after nearly a century of bitter war against the darkspawn hordes, a group of veteran warriors came together in Weisshaupt Fortress in the Anderfels, the western part of the Tevinter Imperium.  They had somehow discovered the process of Joining, and employed it to found a brotherhood that cut all other ties, as a price, in order to dedicate themselves to fighting the darkspawn.  They called themselves the Grey Wardens, and would accept anyone, no matter their race or background, without distinction if only deemed suitable to join the order.

The Grey Wardens first appeared on the battlefield during the attack on Nordbotton, arriving mounted on griffons, plunging into the darkspawn with each Warden taking on crowds of ten or twenty darkspawn at once.  Incredible, they broke the horde and won the battle.  They proved to be a desperately needed spark of hope in the darkest of hours, and quickly gained renown since.  The Grey Wardens started receiving tithes, supples, and recruits from all lands; they grew, building fortresses and functioning as elite shock troops making quick and devastating strikes wherever darkspawn appeared, as well as rallying the mundane armies to greater deeds.

During the next 100 years, humanity slowly managed to stand firm and push back the Blight.  Finally, in -203 Ancient (992 TE), the Grey Wardens gathered an allied army composed of soldiers from the Tevinter Imperium, the tries of the Ciraine (the lands that would become Orlais), and Rivain to confront the main darkspawn horde, led by the archdemon now indentified as Dumat.  The massive battle was waged at the Silent Plains, in what is now southern Tevinter or nothern Nevarra: the legion of darkspawn was defeated and Dumat was slain by the Grey Wardens: with the archdemon's death, the horde's will to fight on was broken.  It took several years to eradicate the remaining darkspawn from the surface, but the deed was done and the Grey Wardens had carved our their legend.  After the battle of the Silent Plains, they were much celebrated and most nations gave formal promises of support for further darkspawn invasions.  The Grey Wardens were also given the Right of Conscription to guarantee sufficient recruits.

*Right of Conscription - Should they need to, the Grey Wardens possess the Right of Conscription; they may demand that any individual from king to criminal be drafted into their ranks.  However -- especially in Ferelden -- this right is used sparingly for fear of political reprisal.  Further complicating matters, the Grey Wardens won't accept just anyone.  Only the best and brightest are invited, regardless of race or social standing.