In May 1633 Imperial forces led by Ernesto Montecuccoli took possession of the castle, which belonged to the Protestant Frederick V of Baden-Durlach an allie of the Swedish King Gustavus Adolphus of Sweden. Montecuccoli was supported by Herman Fortunatus a member of the catholic branch of the House of Baden. Two months later Swedish-Protestant army headed by Otto Louis of Salm-Kyrburg-Mörchingen reconquered Rötteln Castle. Following the Battle of Nördlingen (1634) the Swedish were forced to withdraw their garrison and were replaced later on by an Imperial garrison again. Right after the Battle of Rheinfelden in March 1638 the French-allied mercenary army led by Bernhard of Saxe-Weimar conquered the castle whereby causing severe damages.