The 30 Years War The 30 Years War was a political and religious war that lasted from 1618-1648. It was a conflict between the Protestants and the Catholics in the Holy Roman Empire, which is now Germany. This was started because the Holy Roman Emperor, Ferdinand II decided to abolish the Peace of Augsburg, which allowed the German states to choose whether they wanted to become Catholic or Protestant. This decision angered the Protestants so they decided to revolt. The Catholics then had to retaliate. Both sides ended up making alliances with other countries, which turned this war from being a solely religious war, into an international political war within Europe. France was a major participant in the war. However, despite being Catholic, France decided to fight on the side of the Protestants. The reason they did this is because they feared a united Holy Roman Empire. If the Holy Roman Empire became united, then they may make an alliance with Spain (since both were ruled by Hapsburgs) and attack France from both sides. This was clearly a political motivation for France to join the war because if they were fighting for religious reasons, they should have been on the Catholic side. Catholic Spain was another nation motivated by political reasons. The Spanish saw the war as a chance to attack the Dutch (who joined the Protestant side), whom they have a grudge against. The Dutch revolted against Spain in the past, which led to the Dutch’s independence. The Spanish saw the war as a chance to reclaim the Netherlands.