Why did the Reformation reduce Emperor Charles V’s control over Germany?

The Reformation significantly reduced Emperor Charles V’s control over Germany by empowering territorial princes at the expense of imperial authority.12

As Protestantism evolved into a potent political and military movement, Charles V attempted to enforce religious and political unity through war. However, his efforts to centralize power and limit the autonomy of the estates met with fierce resistance, leading to the "Princes’ War" (1552–1553).12

The resulting Peace of Augsburg in 1555 fundamentally shifted the balance of power. By establishing the principle of cuius regio, eius religio ("he who governs the territory decides its religion"), the settlement granted local rulers the right to determine the faith of their subjects and solidified their control over church properties. Ultimately, the territorial princes emerged as the primary victors of the era, as their authority—now encompassing religious jurisdiction—was greatly expanded. Frustrated by his inability to maintain imperial cohesion, Charles V abdicated shortly thereafter.12