Officer Candidates School (United States Marine Corps)

The United States Marine Corps Officer Candidates School (OCS) is a training regiment designed to screen and evaluate potential Marine Corps Officers. Those who successfully complete the period of instruction are commissioned as Second Lieutenants in the United States Marines. Unlike the other United States military services, the majority of Marine Corps officers complete OCS to earn a commission; the exceptions are midshipmen from the United States Naval Academy, limited duty officers, and inter-service transfers. It is located at Marine Corps Base Quantico.

Depending on the course, Officer Candidates go through either a 10-week (PLC Combined/OCC), or two 6-week courses (PLC) over separate summers, designed primarily to screen and evaluate candidates' fitness to lead Marines by placing them in leadership positions in a stressful environment. The 10-week course only happens after a candidate's junior year of college.[1] Students are evaluated during 2–3 day garrison command billets at the company and platoon level, and squad and fire-team level tactical billets during field exercises.

https://en.wikipedia.org/wiki/Officer_Candidates_School_(United_States_Marine_Corps)