Marine sentries take on serious hardship to earn the honor of standing guard to the President. Not only are they restricted in rank and dependents, but they have three year-long tours ahead of ever getting near the White House.
Sort of like the Old Guard, but Better
Some Marine jobs are elite. These are the kinds of jobs Hollywood likes to depict with lots of action sequences and not a lot of training. You know the type - a Marine is dropped into the middle of the suck and expected to kill dozens of enemies. Then, they're supposed to whittle new weapons from those enemies bones. Those kinds of jobs, and those Marine experiences, are pretty cinematic. But they're not always accurate.
What is accurate is the elite level of discipline and self control it takes to be a Marine sentry.
While most people may crack a smile at seeing the commandant of their branch or a sports team that recently won a championship, the person representing the president is supposed to always be stoically professional.
At any one time, just four highly trained Marines are assigned to presidential duty. These Marines represent not just the Corps, but also the President. They're out in front of visiting dignitaries, Washington elite, and the news cameras pointed at the White House all day, every day.
Globally, sentries provide security at over 100 embassies and consulates. They're usually responsible for interior security. All are trained to react quickly to terrorist attacks along with other security risks like riots, demonstrations, and evacs.
So how do you become a sentry?
Well, your rank has to be between E2 and E8. Also, you have to be eligible for a TS and you have to have a really high score on your ASVAB. Of course, you're not allowed to have any visible tattoos while in uniform. If you're trying to make it into sentry duty and you're an E-5 or below, you have to be single with no dependents.
Once you're selected, you'll attend Security Guard School at Quantico. Marine Security Guard School holds five cohorts per year. Once you graduate, you have to serve three year long tours, one of which will likely be a hardship tour in a third-world country.