Erik VII, ruler of the Kalmar Union, issues his edict of 1422, which permits only Danes to pursue trades and crafts, a blatant move against the power of the Hanseatic League.

The league, fearing loss of trade to Norway (the dominant trading member of the three Kalmar states) and exorbitant trade tariffs, allies with the county of Holstein (still warring with Kalmar over Erik’s 1409 seizure of the duchy of Schleswig), and declares war on Kalmar with the objective of breaking Erik’s monopoly on shipping traffic through the Oresund.

Erik’s forces conquer and successfully hold the western Baltic Sea port of Flensburg in Schleswig; his Danish navy defeats the league’s fleet in the Oresund, and Erik takes control of the entrance to the sound.