Frederick III of Denmark vs King Seonjo of Joseon

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.

Seonjo became king of Joseon at age 15 after the death of his uncle, King Myeongjong. His reign began with hopes for reform, but he soon faced the greatest crisis of the dynasty: the Japanese invasions.

Toyotomi Hideyoshi's Japanese forces invaded Korea, quickly overrunning much of the peninsula. Seonjo fled to Uiju near the Chinese border, abandoning the capital Seoul, which caused widespread panic and criticism.

As Japanese forces advanced, Seonjo fled north to Uiju, leaving the capital undefended. His flight demoralized the Korean military and led to the capture of Seoul by Japanese forces within weeks.

Seonjo requested military assistance from the Ming dynasty of China. Ming forces intervened, helping to push back Japanese troops and eventually leading to a stalemate and peace negotiations that ended the first invasion.

Japan launched a second invasion of Korea after peace talks failed. Seonjo again relied on Ming Chinese forces and Korean naval victories, including Admiral Yi Sun-sin's Battle of Myeongnyang, to repel the invaders.

King Seonjo died after a 41-year reign, leaving a kingdom devastated by war but still independent. His death led to the accession of his son, Gwanghaegun, who would pursue a more pragmatic foreign policy.