Why Dönitz received ten years at Nuremberg

Was Dönitz's ten-year prison sentence justified?

Yes, and he was fortunate it was not more severe given his command responsibility and political role.

Dönitz was fortunate to receive only ten years. The prosecution could not make broader crimes-against-humanity charges stick, while unrestricted submarine warfare created awkward comparisons with Allied practice. Even so, Dönitz had pushed the conduct of the campaign, commanded the navy, and ultimately became Germany's head of state. His sentence shows why legal responsibility at Nuremberg did not map neatly onto wartime naval tactics alone.