Final answer:
England and the Netherlands
Step-by-step explanation:
The Protestant nations that entered the war to help maintain the balance of power were England and the Netherlands. In the context of European history, this refers to the Wars of Religion in the late 16th and early 17th centuries. These wars were driven by religious tensions between Protestants and Catholics, and various Protestant nations, including England and the Netherlands, intervened in order to prevent one group from gaining too much power over others.
Learn more about Wars of Religion