Kingdom Building and Mass Combat Rules

I am looking to start working on a campaign that will involve some kingdom building. For this I am looking for a good ruleset to help this like the Pathfinder Kingmaker rules. I had been looking at the Strongholds and Followers book but after another look through I am a lot less sold on it.

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Does anyone know a good book, set of books, or homebrew that does this in 5th edition?