From Wikipedia

Vietnam
Episode Seven

War on the DMZ

The Vietnamese Demilitarized Zone was established as a dividing line between North and South Vietnam as a result of the First Indochina War.

During the Second Indochina War (popularly known as the Vietnam War), it became important as the battleground demarcation separating North Vietnamese territory from South Vietnamese territory.

The Vietnamese Demilitarizied Zone ran east-west near the center of present-day Vietnam (spanning more than a hundred kilometers) and was a couple of kilometers wide. It reached across into a beach on the east. An island nearby was controlled by North Vietnamese forces during the Vietnam War. Although it was nominally described as being at "the 17th parallel," almost all of the zone lies to the south of the parallel, with only a small portion of the zone near the eastern shore actually including the parallel.

It was around a hundred kilometers north of the city of Huế.

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