His younger brother Wilhelm, regent since 1620, assumed the dignities upon his death. At first also an advocate of Protestant concerns, after the death of King Gustavus Adolphus of Sweden he chose to accord with the 1635 Peace of Prague his Albertine cousins had negotiated with the emperor - against the opposition of his younger brother General Bernard of Saxe-Weimar, who entered into the French service under Cardinal Richelieu. Nevertheless, like many German estates, the Weimar lands were devastated by combat actions as well as by plague epidemics.