According to legend, Danish King Valdemar II set out to conquer the pagan Estonians and convert them to Christianity. During the night of June 15, 1219, the Estonians made a surprise attack on the Danish camp. A red banner with a white cross floated down from the sky, and the Danish archbishop heard a voice say that the Danes would win if they raised this banner. Schools, sports organizations, and Boy Scout troops in Denmark often hold pageants on June 15 in which they reenact the story of the Dannebrog (the Danish flag) and King Valdemar. Discuss
Source: The Free Dictionary