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.
US combat troops entered the Vietnam War in March 1965 and fought for more than eight years until the last US troops left Vietnam on March 29, 1973.