During the Middle Ages, Europe was largely under the command of the Christian Church. The Church had very big power, political, social, economic, and it used it in its advantage in order to control pretty much everything on the continent where it had its power. This unfortunately led to the Middle Ages to become Dark Ages, as the Church was only interested about promoting what was in its interest in order to be more powerful, and it was using very violent methods if someone tried to oppose it. During this period, Europe regressed significantly, and the continent was largely isolated from any new inventions, technologies, scientific progress etc.
The Battle of Jutland is considered to be the only major naval battle of World War One. It saw the British Navy losing more men and ships but remained a powerful tool while it left the German Navy too diminished to put to sea again while the war lasted.