The Military Academy hosts research not available at the Academy -- mainly battle-oriented buffs and debuffs -- with higher levels unlocking more. Crucially it is paid with Tactic Scroll and Gold, NOT Research Stone. Buildable at Keep 36, and it gates the Keep in return: Keep cannot reach 37 until the Military Academy is built (Lv1). Each level needs an escalating Keep level (Lv1 Keep 36 ... Lv15 Keep 50; Lv13 also Rally Spot 48), so it is tightly Keep-coupled end-game content. Research cannot start while the building upgrades. Duty Officer available from Lv1, and importantly the Military Academy duty officer increases research speed at BOTH the Military Academy and the ordinary Academy -- so end-game players run two duty officers (one at each) whenever researching. Ideal Military Academy duty generals: Sargon, Justinian; at the Academy ideally Eulji Mundeok or Hammurabi. Cost/priority: total Tactic Scroll + Gold per level rises steeply through Lv5 (Lv5 ~327k scrolls / ~54.6B gold), but Lv6+ are cheaper per level -- guide recommends minimum research at tier 5 then move to tier 6 first. Lv11-15 costs undocumented. Speed-ups come mainly from killing many bosses. Upgrade resource cost (F/L/S/O) is extremely large. Tactic Scroll and Gold are the binding economic inputs here.
Original research source: Evony Guide Wiki