The Battle of Lützen (16 November 1632) was one of the most important battles of the Thirty Years' War. Though losses were about equally heavy on both sides, the battle was a Protestant victory, but cost the life of one of the most important leaders of the Protestant side, the Swedish King Gustavus Adolphus, which led the Protestant cause to lose direction. The Imperial field marshal Pappenheim was also fatally wounded. The loss of Gustavus Adolphus left Catholic France as the dominant power on the "Protestant" (anti-Habsburg) side, eventually leading to the founding of the League of Heilbronn and the open entry of France into the war. The battle was characterized by fog, which lay heavy over the fields of Saxony that morning. The phrase "Lützendimma" (Lützen fog) is still used in the Swedish language in order to describe particularly heavy fog.