The Ozone layer, which mostly lies on the lower portion of the stratosphere.
How Long Did The Vietnam War Last. The Vietnam War is the longest war ever to have taken place in the American history. It lasted for 16 years and it was terrible for the Americans at that time as the Civil Rights campaign was at its peak and so also the Vietnam War and anti war protests.
Since there was no declaration of the war, exact dates are sketchy. However, it is now widely accepted that the Vietnam War started on November 1, 1955 and lasted until April 30, 1975, which is roughly 20 years, or 19 years, 180 days to be precise.