-Marines are razor-sharp instruments of war, not envoys. They will have no use for diplomacy, as any talks will go through their superiors.
-I do agree however, that even that even the lowliest of Battle-brothers should keep a keen mind in strategy. Along with battle-field tactics, mock campaign training, logistical maneuvering, non-linear thinking exercises, should among others, give our Marines a whole understanding of the intricacies of war.
-History of the the Imperium and the chapter of great importance of course, and should be instructed whole. However, let us not forsake instruction in other fields, such as scribery, natural sciences, oratory, philosophy, and of course, theology. This core of knowledge and understanding will be key to building our Marines to reach their peak, physically, mentally and spiritually, so they will best serve the Imperium in everything they do.