After the great tech wars of the last century, where governments around the planet exhausted their resources in a bid to outdo everyone else in innovation, humanity was on the verge of economic and political collapse. An international meeting on the unsustainability of the public sector convened among the corporate elite, and they mobilized a private task force known as the SENTINELS that quickly dismantled and replaced the weakened governments of the world. Now, the mercenarial militia turn their attention to regulating the peace and ensuring that order and maximum profit for the quickly monopolizing capitalist amalgamate are maintained.
New recruits are either hired from the CIVILIAN population for lucrative pay or drafted from the prison wards in an exchange for reduced sentences - as long as they sign a contract and are able to adequately fill a necessary function, the SENTINELS reject none from their ranks. Biotech branches of the corporations above often work in tandem with the SENTINELS, reducing augmentation costs for recruits and promotees alike.
Theirs is to protect. Theirs is to serve. Some would say that the only thing they are sworn to defend is their paycheck, but the truth is that the world would be in utter chaos without their strong and sometimes firm hand, as well as their increasingly ever-watchful eye, upon it.
Your name, rank and accomplishments will be recorded in the databanks of the SENTINEL Codex, logged for all of time, though your service record blends in with all the rest of your fellow employees.