I am always much more interested in hearing what people with "skin in the game" have to say about almost any topic, and you can't get anymore genuinely invested in results than leaders in combat. The Field Manual has many things going for it:
- It is battle-tested--literally. Over the years, ideas that don't work got weaned out because they could lead to people dying.
- It is written in clear, simple, and direct language. There is no hint of a consultant or professor trying to impress you with the sophistication or originality of his or her ideas, and it is not filled with the self-glorifying tales of ex-CEOs. It is written in simple, declarative sentences that leave no room for ambiguity. Its authors' goals are to clearly and unambiguously share important knowledge.
- It acknowledges that different skills are needed at different levels of any hierarchy and different stages of one's career. It clearly articulates those stages, making it easy to find what qualities are necessary given your leadership circumstances.
My shelves are filled with hundreds of books on leadership; this is the one I keep returning to. If you are a leader or work with leaders, add it to your shelf too.
The US Army Leadership Manual is, I believe, a public-domain publication. The version I have was edited and produced by McGraw Hill in 2004.