Apart from the more theoretical subjects, the others were pretty easy for Rocky to catch up-to.
Battle Strategies and Leadership was a subject that relied 20% on studying history, tactics and past mistakes made by strategist's and 80% on natural charisma and creativity of the individual studying it, and thankfully for Rocky, natural charisma and creativity were both qualities that he had in abundance.
Having experienced a war first-hand and being mentored by the Gods Of War, Ravan, himself. Rocky now had a grasp on how to view a battlefield and how to strategize, as although not completely conventional in his approach, he found creative solutions to every problem his army was put in, during mock practice sessions.