David served three years as an expeditionary physician supporting the United States Marine Corps and has extensive civilian and military overseas experience in Iraq, Kuwait, Haiti, Burma, El Salvador and throughout Africa. Dr. Callaway completed his post- graduate medical training at the Harvard Affiliated Emergency Medicine Residency, Boston where he served as Chief Resident. During this period, he founded the non- profit Operational Medicine Institute (www.opmedinstitute.org) with the mission of improving civil-military coordination, sparking social innovation, and promoting high reliability operations during humanitarian and disaster response.