Frederick III of Denmark

During the Second Northern War, Swedish forces besieged Copenhagen. Frederick III led the city's defense, rallying citizens and soldiers. The successful resistance, aided by Dutch naval relief, saved the Danish monarchy and led to the Treaty of Copenhagen, which established Denmark's modern borders.

After the war, Frederick III staged a bloodless coup, using the Estates' gratitude for his leadership to force through a constitutional change. He abolished the elective monarchy and the Council of the Realm, concentrating power in his own hands and paving the way for the Lex Regia.

Frederick III oversaw the introduction of the Lex Regia (Kongeloven), which formally established absolute hereditary monarchy in Denmark-Norway. This constitution, one of the most absolute in Europe, gave the king unlimited legislative, executive, and judicial power, ending the power of the nobility.