The fourth class [noun] is the freshman class. As a noun, it is two separate words. As an adjective, it is hyphenated.
The fourth-class [adjective] cadet was early to class.
Do not use numerals when referencing.
Refers to the military training and structure of cadet life through which freshmen, or fourth-class cadets, are molded into whole men and women.
The period of indoctrination and training known as Challenge Week begins with the regimental commander announcing, “The Fourth-Class System is now in effect.”
Cadets are also referred to by class year according to academic standing