 After the death of his father in 1771, when his brother the crown prince was abroad, the Caps (party) once again attempted to use him against his brother, now King Gustav III of Sweden, and his mother Louisa Ulrika used this in order to have her own rights as a dowager queen respected by the Caps.Upon the departure of his mother to Prussia, and the return of his brother, however, Gustav III managed to win him to his side.In 1772 he cooperated in the Revolution of 1772 of his elder brother, King Gustav.