Originally Posted by lokariototal
why did Scandinavian countries adopted the cross from the Danish flag (the "Dannebrog")???
My best guess is that they did that because they fought mostly the same enemies. Mediaval heraldry is aside from a battlefield tool also an emblem of unity. The Danish flag, the Dannebrog was a battle-flag during the Baltic crusades of the 13th century.
Sweden and Norway were dominated by Denmark from the late 14th century to the early 16th. It is logical that they adopted a similar flag, like today stars on a flag are in vogue, back then, in Europe, it were crosses.