Machiavelli also wrote a "Discourses on Livy", which mixes politcal philosophy lessons with Roman historical examples.
I'd recommend Plato's "The Republic". "Mencius" (self-titled work by the Confucian philosopher) and maybe Confucius's "Analects" for political philosophy and leadership.
For warfare and strategy, other posters have already said Carl Von Clauswitz's "On War" which is pretty much the gold standard of modern military thought publications so I'm going to reiterate it as a must-read. In particular I would focus on Book I, Chapter 3: "The Genius For War". Slightly less well-known is Alfred T. Mahan's "The Influence of Sea Power Upon History" but that's less about leadership and much more about strategy.
I'd recommend Plato's "The Republic". "Mencius" (self-titled work by the Confucian philosopher) and maybe Confucius's "Analects" for political philosophy and leadership.
For warfare and strategy, other posters have already said Carl Von Clauswitz's "On War" which is pretty much the gold standard of modern military thought publications so I'm going to reiterate it as a must-read. In particular I would focus on Book I, Chapter 3: "The Genius For War". Slightly less well-known is Alfred T. Mahan's "The Influence of Sea Power Upon History" but that's less about leadership and much more about strategy.
A very modern text on tactical leadership would be HJ Poole's "The Last Hundred Yards: The NCO's Contribution to Warfare" https://www.amazon.com/Last-Hundred-Yards-Contribution-Warfa...