In 1963, during of the Cold War, the Danish Post Office and civil defence authorities created a secret 'Emergency Stamp' for use in the event of a major crisis, such as nuclear war. Approximately 200,000,000 of the stamps were printed in secret, the quality being fairly crude as it was not possible to use all the usual printing facilities and equipment. The finished stamps were then packaged up, together with printing plates for any future production, and placed at a number of post offices around the country where their nature and purpose remained a secret, even from the postmasters.
In 1991 it was decided that these stamps were no longer needed. 150,000 of the stamps were made available to the Danish Philatelic Federation, to sell as a fundraising source, all remaining supplies being destroyed. When sold the stamps were accompanied by a small folder illustrating a block of four on the cover and providing background information. Versions of the folders exist in a number of languages but non-Danish examples are now scarce.