Over the centuries there have been men and women like you, who risk their lives to ensure that order and civilization persist across the ages, enduring greed and villainy, ruin and war. When the Foundation Stone was first set at the seat of Moruin in the Castle Moongarm, and the Lords Alliance was forged to protect the realms of men, it is said that a secret order of knights gathered together in the valleys of Arcadia to meet a Justicar of the High People, who also came in secret, and there both the Daemon and Midworlder prayed side by side for guidance from the gods; to determine whether it was right for any Man—human or Yevim—to name himself king of the land, and how they should protect the people from corruption in the highest ranks. And thus these knights swore their allegiance to the Lords Alliance secondarily, that this Order of Mankind should remain forever watchful of those who held the reins of power.
From The Dream of Night, by Goom the Sage, a retelling of Queen Madeleine II's induction of Watchers into the Order of Mankind
The Order of Mankind predates the rebellion against the Emperor by centuries, but its adherents have been among the rebels since its inception. Members of the Order of Mankind are called Watchers, and their numbers are drawn from factions all over the world, across all the races of Midworld.
The Watchers take a sacred oath to protect the kingdoms of men from tyranny, organizing in secret societies, hidden orders, and political subfactions to manipulate the destiny of kings and queens. They have no standing army, and traffic in knowledge.
After The Fall, the Order has been reduced to mere myth, and few remain to carry forward the cause.