Bio, via Department of Defense:

A native of Richland, Washington, Secretary Mattis enlisted in the U.S. Marine Corps Reserve at the age of 18. After graduating from Central Washington University in 1971, he was commissioned a second lieutenant in the U.S. Marine Corps. During his more than four decades in uniform, Secretary Mattis commanded Marines at all levels, from an infantry rifle platoon to a Marine Expeditionary Force. He led an infantry battalion in Iraq in 1991, an expeditionary brigade in Afghanistan after the 9/11 terror attack in 2001, a Marine Division in the initial attack and subsequent stability operations in Iraq in 2003, and led all U.S. Marine Forces in the Middle East as Commander, I Marine Expeditionary Force and U.S. Marine Forces Central Command. During his non-combat assignments, Secretary Mattis served as Senior Military Assistant to the Deputy Secretary of Defense; as Director, Marine Corps Manpower Plans & Policy; as Commanding General, Marine Corps Combat Development Command; and as Executive Secretary to the Secretary of Defense. As a joint force commander, Secretary Mattis commanded U.S. Joint Forces Command, NATO’s Supreme Allied Command for Transformation, and U.S. Central Command. At U.S. Central Command, he directed military operations of more than 200,000 soldiers, sailors, airmen, Coast Guardsmen, Marines and allied forces across the Middle East. Following his retirement from the U.S. Marine Corps in 2013, Secretary Mattis served as the Davies Family Distinguished Visiting Fellow at the Hoover Institution at Stanford University, specializing in the study of leadership, national security, strategy, innovation, and the effective use of military force. In 2016, he co-edited the book, Warriors & Citizens: American Views of Our Military.