A period reference map of the Vietnam theater of operations, showing North and South Vietnam's Corps Tactical Zones, Laos, Cambodia, and the Demilitarized Zone. A hand-annotated arrow near Quang Tri and the Laotian border highlights an area associated with covert cross-border reconnaissance operations conducted by MACV-SOG (Studies and Observations Group) during the war, such as the 1970 Operation Tailwind in southeastern Laos. Project: 219439