In 1772 he cooperated in the Revolution of 1772 of his elder brother, King Gustav. He was given the task of using his connections in the Caps party to neutralize it and secure the southern provinces by use of the military, tasks he performed successfully and for which the king rewarded him with the title Duke of Södermanland.
In 1772 he cooperated in the Revolution of 1772 of his elder brother, King Gustav He was given the task of using his connections in the Caps party to neutralize it and secure the southern provinces by use of the military, tasks he performed successfully and for which the king rewarded him with the title Duke of Södermanland.