Denmark rule of Schleswig and Holstein

In 1218 King Valdemar II of Denmark supported Holy Roman Emperor Frederick II.
Valdemar II was rewarded with the Emperor acknowledging Denmark rule of Schleswig and Holstein.
Suppose King Valdemar did not support Frederick II.
Which nation shall rule Schleswig and Holstein?
 
I was under the impression Schleswig was already controlled by the Danish at the time it was made a duchy.
 
I was under the impression Schleswig was already controlled by the Danish at the time it was made a duchy.

It was, yes. Cnut the Great agreed that the border of denmark and the empire in 1027 was at the eider river between schleswig and holstein as did charlemagne in 811.
 
Top