Only capitalize “cadets” when used as a title (Cadets Sanderson and Salazar) or as part of the phrase “Corps of Cadets,” not as a common noun (The cadets leave for winter furlough after their last exam.).
Upper-class cadets of high academic and military standing selected to train freshman cadet recruits. Collective noun, singular in usage but plural in function.
The cadre is responsible for training and motivating the incoming class.