Lieutenant Colonel Josh Simpson assumed command as the Inspector-Instructor for Marine Corps Advisor Company Bravo and Site Commander for Site Support, Concord, California, on 9 July 2021.

Lieutenant Colonel Simpson was commissioned a Second Lieutenant in the United States Marine Corps in May 2002 after graduating from Virginia Polytechnic Institute and State University. Following graduation from the Basic Officer Course and Infantry Officer Course, Lieutenant Colonel Simpson served as a platoon commander with 1st Battalion, 6th Marines, deploying in support of Operation Enduring Freedom and Operation Iraqi Freedom. In 2006, Lieutenant Colonel Simpson transferred to The Basic School where he served as a warfighting instructor, staff platoon commander, executive officer, and Infantry Officer Course instructor.

Lieutenant Colonel Simpson was accessed to the Active Reserve program in 2012 and retrained as a financial management officer. Active Reserve assignments include Reserve Personnel Marine Corps Program Manager for the Reserve Affairs Personnel Policy, Plans, and Programming Branch at Manpower and Reserve Affairs and Military Deputy Branch Head for the Manpower Budget Branch at Programs and Resources.

Lieutenant Colonel Simpson earned a Bachelor of Arts from Virginia Polytechnic Institute and State University, a Master of Business Administration from Wake Forest University and the Naval Postgraduate School, and a Master of Science from the Eisenhower School for National Security and Resource Strategy.