Mattis is a graduate of the US Marine Corps Amphibious Warfare School, US Marine Corps Command and Staff College, and the National War College. He is noted for his interest in the study of military history and world history, with a personal library that once included over 7,000 volumes, and a penchant for publishing required reading lists for Marines under his command. He required his Marines to be well-read in the culture and history of regions where they were deployed, and had his Marines deploying to Iraq undergo "cultural sensitivity training". According to an article published in 2004 by the "Los Angeles Times" it was his concern for the enlisted ranks along with his energy and enthusiasm that garnered him the nickname "Mad Dog". But in 2016, when President-elect Trump asked Mattis if his nickname was indeed "Mad Dog," Mattis replied, "No, sir," saying that his actual nickname was "Chaos."