"The Art of War" by Sun Tzu

If you've never read the book, you should at least listen to the 21 principles because they don't just apply to the military and can be used in every day life. I have an excellent hardback that I bought at a thrift store that also includes case studies of modern wars and points out how The Art of War applied. If you ever wonder why the USA keeps losing wars, or why the Democrats can't seem to win elections - this book gives you the answers. You can find an audiobook version on YouTube but they usually last around an hour. Here's a shorter version that just covers the 21 principles in under 15 minutes.