While other war, and boardgames, dealing with empire-building, had clear mechanics on how to establish and develop your territory, the OD&D guidelines are far murkier. This is complicated by the fact that various levels of abstraction coexist at this level of the game.
For example, when building your stronghold using the OD&D rules, there are certain configurations and related prices for each of the different components of your stronghold. The towers are a certain price, the gates are another, as are the sections of walls, different-sized buildings, and so on. I consider these OD&D stronghold construction guidelines to be at a intermediate level of abstraction: at a lower level of abstraction, you might define your building method, or the materials you used for the walls, from what quarry you obtained your stone, the way you laid the foundation, who you hired to oversee the construction, how many labourers worked (and were killed) during the construction, and so on.
And once you have constructed your castle, you apply an even higher level of abstraction to the operation of your territory. Now you include the area around your stronghold, using the Outdoor Survival maps, and each hex that you control provides you with a certain number of gold pieces, representing the taxes you collect from the towns and villages that surround your castle. Forget that the towns and villages may already have a ruler, or that the area you have built your stronghold in may be composed entirely of wilderness. Also, you don't track the activities of the tax collectors, or what products or activities your towns are engaged in producing.
All of this coexists with the lowest level of abstraction: your character, her equipment, personality, and the minutia of interactions between the characters themselves, not to mention any further adventuring or dungeon-delving.
Thus, at least three levels of abstraction co-exist in the OD&D endgame. Then we add a further consideration: the amount of space allocated to providing guidelines to the players and DMs on establishing and operating your stronghold may only amount to two or three pages between the three "little brown books" and the supplements.
While this allows a great deal of room for DM and player interplay and negotiation, it would have been nice to have had some economic, political and military guidelines as a basic underpinning.