Gustavus, kings of Sweden. Gustavus I, 1496-1560 (r.1523-60), was the founder of the modern Swedish state and the VASA dynasty. After his father, a Swedish senator, was killed (1520) in a massacre ordered by the Danish king, CHRISTIAN II, Gustavus escaped from prison and defeated the Danes. His election as king by the Riksdag (1523) ended the KALMAR UNION of Denmark, Sweden, and Norway. In 1527 he founded a national Protestant Church. With a newly strengthened navy he defeated LÜBECK (1537), freeing Swedish commerce from the power of the HANSEATIC LEAGUE. In 1544 he made the throne hereditary in the Vasa family, ending the election of Swedish kings. His son Eric XIV succeeded him. Gustavus II (Gustavus Adolphus), 1594-1632 (r.1611-32), was the son of CHARLES IX. Aided by his chancellor, OXENSTIERNA, he ended the Kalmar War with Denmark (1613) and forced Russia to cede Ingermanland (1617). In the THIRTY YEARS WAR he obtained much of Polish Livonia and several Baltic ports (1629), then invaded German Pomerania, defeating TILLY near Leipzig (1631). At Lützen (1632) the Swedes defeated WALLENSTEIN, but Gustavus was killed. His daughter, CHRISTINA, succeeded him. Gustavus III, 1746-92 (r.1771-92), was the son of Adolphus Frederick. To quell civil strife, he imposed (1772) a new constitution restoring the royal prerogatives lost by his successors. In a war with Russia and Denmark (1788-90) he was victorious. He planned a coalition to aid the French royalists but was assassinated by an agent of the nobles.