Recruit division commanders, known as RDCs, are the drill sergeants of the United States Navy. Before they train Navy recruits at boot camp, future RDCs must graduate from Continuation School, or C School, at Naval Station Great Lakes near Waukegan, Illinois, about 40 miles north of Chicago.

Business Insider spent four days at RDC C School to see how recruit division commanders are trained to instruct the next generation of sailors.

RDCs distinguish themselves from other Navy personnel with a red rope they wear around the left shoulder of their uniforms. They're responsible for training and mentoring Navy recruits during their time in boot camp.

During the 13-week C School course, RDC students learn how to motivate recruits, inspect their barracks, and lead them in physical training.