How would you write martials getting followers and a stronghold as a class feature?

For those unfamiliar, at higher levels in very early D&D martials used to gain an interesting form of utility, getting land and building say a castle on it, getting dozens to hundreds of followers based on level. It's often suggested in threads about how much less useful martials are than casters, as they lack their level of ability to contribute out of combat - and while obviously it doesn't fit every character, if ever implemented it should be one choice out of several which don't involve externalising power, it's an interesting solution.

But how on earth would you actually implement it?