Why did Frederick II preserve the power of the Prussian nobility?

Frederick II preserved the power of the Prussian nobility—the Junker class—primarily because he believed the continued existence of the state depended on their cooperation.1

Frederick viewed the nobility as the most essential social group, possessing a unique sense of personal honor and responsibility. His reliance on them was structural and practical:1
* Military Leadership: The nobility provided the vast majority of the army’s officers, including virtually all high-ranking positions.1
* Administration: They filled the majority of government official roles and ministerial posts, while also dominating local government in the countryside.1

Because the regime could not function without their support, Frederick safeguarded their interests, such as preventing the dilution of noble status by self-made bourgeois and protecting noble-owned land from being purchased by the urban middle class. While Frederick personally disliked serfdom, he avoided significant social reforms because he realized that challenging the nobility risked disrupting Prussia’s agricultural life and eroding the foundation of his state.1