How did Prussia become a seperate power from the Holy Roman Empire and the Hapsburgs?

Question

when and how?

Answer 1

The electors of Brandenburg, together with the other electors, palyed an important (if after the 30 years war mostly ceremonial) part in the confirmation of the Holy Roman Emperors (who, with very few exceptions, had been Hapsburgs since Frederick III in the 15th century). In 1700, the then elector of Brandenburg declared himself king in (later: of) Prussia, a territory outside the Holy Roman Empire. Since Frederick I, all kings of Prussia also ruled in Brandenburg (i.e. within the Holy Roman Empire), just as the Hapsburg emperors were at the same time rulers of territories outside the Holy Roman Empire (e.g. as kings of Hungary). So the territory of Prussia proper had always been outside the Holy Roman Empire.