Question not your purpose or whom you serve.

The Sentinels were formed after the Raven Wars. The Raven Wars were started when AC pilots, called Ravens, turned against each other to gain power. Cities were leveled; millions of deaths; and millions more of lives ruined. The goal of the first Sentinels was to arrest and execute the surviving Ravens.
The Sentinals completed this mission and restored order to the world. The surviving Sentinels resumed the role of the Ravens in a different matter. The Alliance was formed and the Sentinels made its military and police forces.
The leader fo the Sentinels created a system to help the process. Future Sentinels were to picked as newborns, the knowledge they will need are then implanted into their brains at the age of 4-6. Physical and weapon training begins at age 7 till their 18. Then they're given their first mission in teams of 10. Most of the time 6 out of 10 cadets die. The remaining 4 are formed into a team known as a Tactical Squad.
The Sentinels are experts in long, medium, and hand-to-hand combat. They are armed witht he best weapons, and have the best training.
There are 2 ways out of the Sentinels: in a body bag, or to become a runner (deserter basicly).
There has been only 3 runners in the history of the Sentinels, and all of them have been found and executed.
Commissars are the ones responsible to pick and train future Sentinels. They are also responsible to execute any who do not meet the requirements.
The Librarium are the ones responsible for holding, keeping, and portecting the relics and history of the Sentinels. They are alos responsible for handing out Security Passes to the masses. Without these passes the people would not be able to do anything, and it's impossible to forge a pass.

Ruling Body:
The High Lord: Arminius
Lord Commander Militant:
Lord Commander:
Warmaster:
Lord General Militant:

Lower Staff:
Lord General:
General:
General:
Commissar:
Commissar:

Librarium:
Imperator Librarius:
Invictus:
Librarian:
Librarian: