Digging through the subject matter of military operations (or 'expeditions' as I'm calling them), it's quite clear how much has changed in the description of battlespace mechanics since the Vietnam War. Thankfully, I'm not on the hook to explain the ins and outs of modern operations theory (like I could!) - but I am left with the task of walking back those theories to produce role-playing rules for its more primitive ancestor.
Hammering down the content is the best I can hope for with this post. Content? Basically, what features of managing, organizing or effecting a battlefield do we want to include in the system? Before getting to that, first I want to make a distinction between 'strategy' and 'expedition' where it comes to the skill set the player can steadily acquire. And while we're at it, we might as well also distinguish tactics.
Strategy describes the entire war. If Sauron is attacking Middle Earth, his strategy is to encourage Saruman to raise and army and smash the threat Rohan presents, particularly any chance that Rohan might support Gondor. If Saruman can ruin Rohan, then Gondor will be alone. There's not much more to the plan than this in the book; presumably, however, Mirkwood and other friendly groups to Sauron are doing something. Moreover, the timing is such that the candy-ass elves are in the mood to weep home to the west.
Expedition describes the actual attack on Osgiliath in order to secure it as a ford across the Anduin, enabling the deployment of the Witch-king of Angmar's forces on the field before Gondor. Laying out the battle plan for the field is a huge task, for deciding which group stands where and who attacks from which flank demands a peculiar set of skills quite apart from those of strategy. Since Sauron is busy with strategy, W.K.A. has the duty.
Tactics describes the orc troop who fell upon Boromir and killed him before spiriting away Merry and Pippin. In the novel there is no name given to the leader of the orcs; but of course this was to dramatically highlight the surprise and horror of Aragorn finding Boromir dead and full of arrows. We know there would have been a leader, someone who chose the right moment to attack the Fellowship when they were scattered. This skill at directing a few persons - effectively the party attack patterns in ordinary D&D - is called tactics.
As a set of general headings that might serve to systematize what parts of expeditionary force should matter to us, I propose the following: agility, efficiency, situational awareness, intelligence, surveillance, reconnaissance, environment, tactical responsibility, chain of command, units and logistics.
Agility is the speed of getting of the force to the place where we want it while maintaining a fighting trim. Efficiency is both the combat effectiveness and resilience the force has in obtaining the desired goal. Situational Awareness is our capacity to understand what is going on during the actual battle, enabling us to make changes as needed. Intelligence is what we know about the enemy. Surveillance is what we can see. Reconnaissance is the process of learning about what we do not know and cannot see prior to full commitment. Tactical Responsibility describes what duties we give to what part of our army, particularly in terms of what geographical area a given unit is responsible for. Chain of Command describes who we trust, who they trust and how much control we have over people we will never personally address. Units are the subdivisions of our force. Finally, Logistics describes the physical support of our force in terms of tools, supplies, transport, housing and rehabilitation (medical and otherwise).
These are, for the most part, too fiddling to manage from a strategic standpoint - that is why the actual problem of taking down Gondor is not managed by Sauron personally. Politically, the method for capturing a given goal in war is handed over to a trusted general - this was ever more true prior to the 20th century, when communications between an army and the political head of the country was non-existent. It is also the reason many kings went along or led the army personally, though this wasn't required or even standard practice. Edward III let his son Edward the Black Prince smash the French at Crecy and Poitiers, probably without knowing much at all of what was going on. Justinian of Byzantium sent Belisarius to reconquer the Mediterranean and did not jog his elbow. Fernando Alvarez had effectively carte blanche in the Netherlands, provided he filled the coffers of Charles V and Philip the II. The lesson here is that, unless we are willing to take the risks of getting killed or captured in battle personally, we have to accept that whatever we send the general off to do, the general will make up his or her own mind about how to do it.
Conversely, most of the above terms do apply to tactics, but in ways comparatively simple to moving whole army. Agility also applies to two soldiers crossing a line of fire to get behind a boulder, but this has is massively different from getting an army across a river. Characters in D&D tend to have perfect situational awareness (since we can slow down time as much as we need and all, plus looking at the battle map from above and in at any angle that pleases us), but in the midst of a battle, with people shouting information at a commander continuously and waiting for orders, 'seeing' what's going on even at the level of a squad assaulting a tower is an impossibility. There is too much situation to allow complete awareness. Characters practice logistics when they stop at the market to buy two weeks of rations; hauling two weeks of rations for five thousand soldiers and the support companies behind them is an incomprehensible nightmare, even if they're only five miles from a big city and there's actually enough food available. Doing it on time and without considerable waste is incomprehensibly difficult, especially when we calculate in theft, corruption, incompetence and sheer human distrust and stupidity. This explains why armies prior to modern transport/communication apparatus consisted largely of roving thuggery. It is better than starving.
So, how do we set up a rule system to handle these Ten Things for players? You got me. But I'll have it worked out by the time I have to start building the ability-set in the wiki. The secret is starting small and concentrating on only one bit at a time.