[2] As the intended successor to Field Marshal Duke Louis Ernest of Brunswick-Lüneburg, who had left the Netherlands in October 1784, he played a significant role in the conflict between the Dutch Patriots and Orangists until mid-September 1787.
Later, he commanded several Free Corps in Utrecht until the Prussian invasion of Holland in 1787 strengthened the position of the Stadtholder William V of Orange again.
Criticism of Salm's military judgment arose primarily due to the hasty evacuation of Utrecht; afterwards, he was often referred to as a "stylish failure".
[3][4][5] Contemporaries such as the Duke of Brunswick, his former adjutant Quint Ondaatje, August Ludwig Schlözer, and General Von Pfau,[6][7][8][9][10] as well as many other German historians, hold a different opinion.
[18] Johann Friedrich's military career took him into the French army, where he held the rank of Maréchal de camp.
[23][24] They were dominated by the oppositional Patriot movement, which fought the quasi-monarchical position of the stadtholder in the Dutch Republic of the United Netherlands.
Johann Friedrich played an important role as a military leader of the Dutch Republic during the era of the Patriots as a negotiator with the Austrian emperor Joseph II, to dismantle the Barrier treaties 1709-1715.
He might have held out in Utrecht for a considerable time, but he surrendered the place without firing a gun, literally run away & hid himself so that for months it was not known what was become of him.