"When this banner is raised on high, you shall be victorious!" - The Dannebrog and the Battle of Lyndanisse

15 June 1219, during the Northern Crusades, the Danish King Valdemar II defeated the Estonians near present-day Tallinn, allegedly with divine aid and the future Danish national flag, the Dannebrog, falling from the sky.

“A voice was heard to say "When this banner is raised on high, you shall be victorious!" (Peder Olesen)

The Danish painter Christian August Lorentzen’s (1749 – 1828) Romantic interpretation of the “Dannebrog falling from the sky during the Battle of Lyndanisse, June 15, 1219“ (1809)

Since the Norse had developed their famous clinker built, ocean-going ships around 800 CE and discovered that they had with the Austmarr, the East Lake, a wonderful traffic route to all the riches along the shores of the Baltic Sea and beyond to the Black Sea and Constantinople, the Scandinavian expansion into the Baltic rim began with a vengeance. Fortunately for empire-building ambitions, the stubborn natives of the region refused to see the light and become Christians like the Norse did after 1000 CE, and an ideological justification was added to the eastward expansion, just like the one the Holy Roman Empire had east of the Elbe – conversion of the heathens with fire and sword. And after a few moderate successes, Pope Celestine III called for a crusade in the North and the Danes, Swedes and the Holy Roman Empire with the newly formed Teutonic Order followed and began to subjugate North-Eastern Europe.

Prelude to the Danish involvement in the Northern Crusades:  "Bishop Absalon topples the god Svantevit at Arkona in 1169", as imagined by the Danish painter  Laurits Tuxen around 1890

The spring of 1219 saw the Danish King Valdemar II landing on the shores of Revalia in northern Estonia on the eastern shores of the Baltics, allegedly with more than 1.000 longboats and about 2.000 fighting men. The native Estonians fled from the nearby village of Qalaven, the Danes constructed a castle on the spot, called Taani (Danish) linn (town), Tallinn, by the locals and thought that everything was well and proper until the Estonian tribesmen returned in force. Obviously, the tribal warriors were quite well mannered, since they waited until after suppertime to strike out against the Danes who might have been pigged out, since they were hard-pressed pretty soon. However, so the legends tell us, as long as Anders Sunesen, the Archbishop of Lund, held his arms aloft in prayer, the Estonians could not move in for the kill. When the bishop let his arms sink in exhaustion, the rest of the clergy present helped him to raise his arms again and at that moment a banner fell from the sky, a white cross on a red ground, and with that banner and a sudden counterattack led by Valdemar’s Wendish vassal Vitslav, the Danes managed to save the day, win the battle and conquer all of Estonia afterwards.

Earliest known version of the Dannebrog from around 1370

The Dannebrog, the Danish cloth that had wondrously appeared during the Battle of Lyndanisse, is historically documented during the reign of King Valdemar IV Atterdag in mid-14th century for the first time and thus one of the oldest national flags still in use. The legend itself was first recorded during the 16th century, about the time when the original banner was lost by King Hans while campaigning in Holstein, and it is, of course, pagan slander that Danish Vikings already had used red flags called Dannebrog around the year 1000 to advertise their origins.