In the 1960s as the threat of nuclear war loomed over the United Stated and Russia very strong measures were taken. Operation Chrome Dome was strategic mission put in place by the US Air Force where 12 B-52s would circle the globe within striking range of Russia. They mainly served as a deterrent, but if nuclear war broke out then they would be in a position to strike. Fortunately, these bombers never actually needed to launch an assault but there were still some severe issues along the way.
In January of 1961, a B-52 was departing from Seymour Johnson Air Force for its routine mission in Operation Chrome Dome. As the B-52 was in flight it began to experience issues with structural integrity and broke apart. Some of the crew aboard managed to eject but there was a much bigger problem, one of the bombs has dislodged.
One of the Mark 39 nuclear bombs deployed from the B-52 and fell to the Earth. It seems like all was lost as the thermonuclear device plummeted towards American soil, but when it hit there was no explosion.
Crews discovered the warhead stuck in a tree in the middle of a bog in near perfect shape. As luck would have it, one of the five safety switches did not engage preventing the Mark 39 bomb from detonating. The Goldsboro B-52 incident is explained in further detail in this short video narrated by Adam West.