Xenophon 
The Cavalry General [PDF ebook] 

Xenophon the Athenian was born 431 B.C. He was a pupil of Socrates. He marched with the Spartans, and was exiled from Athens. Sparta gave him land and property in Scillus, where he lived for many years before having to move once more, to settle in Corinth. He died in 354 B.C.
      
           The Cavalry General is a discourse on the merits
           a cavalry general, or hipparch, in Athens should
           have. Xenophon also describes the development of
           a cavalry force, and some tactical details to be
           applied in the field and in festival exhibition.
This book holds a lot of wisdom that could be put to good use in today’s world very easily, in war and also other endeavors.