Adolf Hitler had high hopes for his conquest of Norway, which held both great symbolic and great strategic value for the Fuhrer. Despite early successes, however, his ambitious northern campaign foundered and ultimately failed. Adam Claasen for the first time reveals the full story of this neglected episode and shows how it helped doom the Third Reich to defeat.

Hitler and Raeder, the chief of the German navy, were determined to take and keep Norway. By doing so, they hoped to preempt Allied attempts to outflank Germany, protect sea lanes for German ships, access precious Scandinavian...