query: Who was the last ruler of the Swedish Empire?
passage: Swedish Empire
Despite these setbacks, Charles XII twice tried to invade Norway to force Denmark-Norway out of the war again. On November 30, 1718, King Charles XII was mortally wounded during the siege of Fredriksten Fortress in Fredrikshald, today's Halden. With his death, Swedish war efforts mostly came to a halt, although Russia continued to harass the civilian population of the Swedish coastal areas until the concluding Treaty of Nystad was finally signed in 1721. Sweden would remain a regional power of varying success until the 19th century, but the Great Northern War put an end to Sweden's time as a great power.
passage: Christina, Queen of Sweden
Christina (18 December 1626 – 19 April 1689), the only surviving legitimate child of King Gustav II Adolph and his wife Maria Eleonora of Brandenburg, reigned as Queen of Sweden [note 1] from 1632 until her abdication in 1654.[7] At the age of six,[8] Christina succeeded her father upon his death at the Battle of Lützen, but began ruling the Swedish Empire when she reached the age of 18 in 1644.