Retired General Stanley McChrystal, a former head of the Joint Special Operations Command (JSOC) and commander of all forces in Afghanistan, recently co-wrote a book on leadership, exploring what makes an effective leader.

The book, “Leaders: Myth and Reality,” explores a wide range of leaders across centuries of human history. The authors’ selection of leaders isn’t limited to military men. They explore the leadership traits and styles of business owners (such as Walt Disney and Coco Chanel), artists (such as Leonard Bernstein), politicians (such as Margaret Thatcher), scientists (such as Albert Einstein), civil-rights advocates (such as Martin Luther King Jr. and Harriet Tubman), and even terrorists (such as his former opponent Abu Musab al-Zarqawi, the bloodthirsty founder and leader of al-Qaida in Iraq). One of the more prominent leaders the book examines is Confederate General Robert E. Lee, a personal hero figure for McChrystal.

The book’s overall thesis is that different environments necessitate different styles of leadership and that people tend to choose leaders they need. Furthermore, McChrystal and his fellow authors assert that current and prospective leaders shouldn’t endeavor to memorize a list of leadership qualities but rather to understand how to interpret different situations and then determine what sort of leadership is required.

McChrystal’s co-authors are Jeff Eggers, a former Navy SEAL and special assistant for national security affairs to President Obama, and Jay Mangone, a Marine Corps veteran and experienced researcher currently serving as principal researcher at the McChrystal Group.