Redbeard
Banned
Why was Denmarck Germanys "vassal" at that time ?
(Sry if I ask. It's just, that I'm rather uneducated about denmarcks situation at that time.)
After 1864 there were serious considerations if Denmark could survive as an independent nation at all, and anyway it was learned that we were alone vs. Germany. I.e. don't expect any help from the other Scandinavian countries, GB, Russia or France. So in order to survive accept your part in the greater German security policy.
In public a lot of people still believed the next war would be against Germany and in a way the Danish defence policy of fortifying Copenhagen/N. Zealand and leaving the rest undefended also was a kind of insurance vs, German intervention, as a fortified Copenhagen would be an equally difficult nut to crack for Germany and GB, but by 1914 there was no doubt that the Danish role was securing the German North flank from a neutral position.
Part of it probably also was founded in a reasoning about North Slesvig. The German government had promised that some when in the future a referendum would beheld about the relation to Denmark or Germany and if Germany won the Great war you better be in good standing and if they lost you could anyway get what you wanted if not being too blatantly German.
After WWI the French actually offered Denmark to take as much of N. Germany as we could swallow, but luckily the Government was wise and went for a new border following the 1920 "language border" as closely as possible.