Emblems of the Kalmar Union explained

The Kalmar Union was the personal union of the kingdoms of Denmark, Norway and Sweden during the 15th century. The first king of the Kalmar Union was Eric of Pomerania. His seal combined the coats of arms of Norway (center, as an inescutcheon upon a cross over all), Denmark (in dexter chief), Sweden (the Folkung lion, in dexter base) and Pomerania (a griffin, in sinister base), and in addition the Three Crowns symbol in sinister chief; the latter heraldic design predates the Kalmar Union, and is now mostly associated with the coat of arms of Sweden, but which during the 15th century came to represent the three kingdoms of the union.^{[1] [2]}

In two letters dated to 1430, Eric of Pomerania orders the priests of Vadstena and Kalmar to wear the "banner of the realms" on their robes. The banner is described as "a red cross in a yellow field".^[3]

Notes and References

1. Book: Alverdens heraldik i farver . Sven Tito Achen . 1972 . Politikens forlag . Danish . Copenhagen . 87-567-1685-0 . 216 . Sverige.
2. Book: Alverdens heraldik i farver . Sven Tito Achen . 1972 . Politikens forlag . Danish . Copenhagen . 87-567-1685-0 . 217 . Sverige.
3. "Sources are scant about the Union of Kalmar flag. These are a couple of brief passages of text. There is no pictorial evidence attesting to the Union flag from the time of the Union of Kalmar (though some authors point to heraldic evidence for a red union cross) and definitely no surviving flag. A flag seen by Hugh Watkins in a museum showing a red Scandinavian cross on a yellow field is a recreation of what is thought to have been the union flag. (Jan Oskar Engene, 11 February 2004) "What remains of evidence is two letters from 1430 in which King Erik orders the priests of Vadstena and Kalmar to wear the "banner of the realms" on their robes. The banner is described as 'a red cross on top of a yellow field.'" (Jan Oskar Engene, 16 February 2004)crwflags.com