This is a leaflet produced by the British government in 1957 and intended to be airdropped over the Pacific Ocean. Unlike most airdropped leaflets, this one isn’t propaganda – it’s a very real warning to get out of the area, or risk being nuked.
Operation Grapple was a series of nuclear weapons tests carried out by the UK in the Pacific from 1957 to 1958. The first tests, Grapple 1, 2 and 3, featured Britain’s first ever thermonuclear weapons – what most of us know as hydrogen bombs. Up to this point, Britain had had fission (‘atomic’) bombs, but H-bomb tests by the U.S. and Russia in 1952/53 meant the UK had to be seen to be up-to-speed. Britain had to test its own H-bomb or risk losing its place on the world stage.