The House of Vasa was the Royal House of Sweden (1523-1654) and of Poland (1587-1668). Gustavus II Adolphus Vasa inherited a feud with the Polish ruling line of Sigismund III Vasa, who was deposed as king of Sweden in 1599. Sigismund started a series of protracted wars to regain the throne. Gustavus himself began the next round with an invasion of Livonia, kicking off the Polish-Swedish War (1625–1629). Protestants suffering through the Thirty Years' War asked Gustavus to intervene. Christina, Gustavus's sole legitimate issue, abdicated the Swedish throne in 1654, six years after the end of the Thirty Years' War.