The Vikings flew flags on their ships but these did not have much resemblance to the presentday national flags of the Nordic countries. The Vikings picked up the habit from the Arabs who got the idea from the Chinese. For the Chinese the colors of their silk flags represented philosophical and religious concepts, while the Arabs and Vikings used the colors to represent dynasties and individual chieftains.

The general design of the Nordic flags was born when medieval knights started using banners with crosses on their third crusade to the Holy Land at the end of the 12th century. The early flags were square, just like the Swiss flag, but then they were extended from Sweden’s 10/16 to the Åland Islands 10/19 proportions.

The Danish flag is the first Scandinavian flag to be established but many Danes also claim it to be the oldest national flag in the world.

According to legend the Dannebrogen (Flag of the Danes) fell from heaven during the battle of Lyndanisse in Estonia in 1219. As long as the Danish bishop kept his arms up in the air praying to God, the flag did not hit the ground. Thanks to the flag the Danes were victorious over the heathens. This dramatic scene was described by the Franciscan monk Peder Olsen in 1527 and it became the motive of a famous patriotic painting by C.A. Lorentzen (in 1809) that all Danes know from their history books.

The same flag that was victoriously brought back to Denmark tied to a ship’s mast, was lost by King Hans in battle in 1500. 59 years later King Fredrik II won it back in another battle and had it hung up in the Slesvig Cathedral in present day Germany.

The first depiction of Dannebrogen is on Valdemar IV Atterdag’s coat of arms in 1390. Historians believe that he was the first Danish king to use the Dannebrog. It is believed that he first saw the red flag with the white cross, that was then the banner of the Holy Roman Empire, when he was growing up at the imperial court. The design goes back to Emperor Constantine’s dream of a cross before the battle in 312 in which he became absolute monarch of the Roman Empire and converted to Christianity. His vision of the cross (with the words "under this sign you will be victorious") was used by the Portuguese Order of Christ in 1318 and by others in their crusades against the Moors. The same design and phrase also appeared on Portuguese coins and was later copied by Christian IV on Danish coins.

Today the Danish flag is honoured on Valdemar Day June 15 in commemoration of the day in 1219 when the flag fell from the sky, as well as, the reunification with Southern Jutland in 1920. Danes love their flag and fly it at their homes and even decorate Christmas trees with miniature versions. Weddings, anniversaries and birthdays are traditionally marked with the national flag and it is not unusual for birthday cakes to be decorated with small paper flags.