ABOARD A U.S. MILITARY AIRCRAFT — Before taking the highest office in the Pentagon, Defense Secretary James Mattis was already a prolific reader, boasting a library of more than 7,000 books and frequently revisiting a handful of titles for reference.
Despite his increased responsibilities and demanding schedule, Mattis' extraordinary reading habits haven't slowed.
He's currently reading "Earning the Rockies: How Geography Shapes America's Role in the World" by Robert D. Kaplan and "Partners in Command: George Marshall and Dwight Eisenhower in War and Peace" by Mark Perry, chief Pentagon spokeswoman Dana White told CNBC as the secretary wrapped up a five-day trip around the world.
Mattis, a revered Marine with a military career spanning four decades, credits his leadership success to his voracious reading habits.
"Thanks to my reading, I have never been caught flat-footed by any situation, never at a loss for how any problem has been addressed before. It doesn't give me all the answers, but it lights what is often a dark path ahead," Mattis wrote in a 2003 email to military historian Jill Russell.
Hailed for his battlefield prowess and kinship with rank-and-file servicemembers, Mattis explained that the best way to hone war-fighting skills is to leverage lessons learned from history.
"A real understanding of history means that we face NOTHING new under the sun," Mattis wrote. "We have been fighting on this planet for 5000 years and we should take advantage of their experience. Winging it and filling body bags as we sort out what works reminds us of the moral dictates and the cost of in competence in our profession."
Before Mattis became President Donald Trump's Defense secretary, the four-star Marine Corps general led the U.S. Central Command, the combat command responsible for the wars in Iraq and Afghanistan.
Throughout his military career, Mattis was affectionately referred to as "Mad Dog" and "warrior monk." He was known for his strategy, matter-of-factness and disdain for PowerPoint, which is recognized as the U.S. military's signature teaching tool.
Instead, Mattis chooses to arm himself with books.