After studying forestry and economics, he served with the 5th Reserve Mountain Battalion during
World War I and retired from military service in 1919 with the rank of oberst. He then managed the Hohenzollern estate in Umkirch near Freiburg im Breisgau until his father's death in 1927. During the 1920s he was engaged in a dispute with the SPD Government over the use of his princely title and royal surname. The District President of the province of Hohenzollern, Alfons Scherer, informed the authorities in a circular dated July 9, 1928 that after the death of his father, Frederick had no right to either the predicate Highness nor the title Prince of Hohenzollern, arguing that the title had expired in 1927 with the death of Wilhelm Prince of Hohenzollern. This was resolved when Frederick threatened the city of Sigmaringen with moving his administration to Munich, prompting Minister of the Interior
Carl Severing to put Scherer on leave. Despite the adverse conditions during the global economic crisis of the early 1930s, Frederick managed to secure ownership of the family properties and its businesses, especially the extensive forest holdings in East Germany. He managed to buy back part of the art treasures that his father had already sold and thus save the Hohenzollern art collection. Frederick was honorary chairman of the Silesian Maltese Knights of Law and head of the
Stahlhelm in Württemberg and Baden. His affinity for cultivating military traditions led to a
rapprochement with the Nazis. His younger twin brother joined the SS and in 1935 the Nazi state awarded Frederick the title of Royal Highness. He was however forbidden to serve in the German military because of Hitler's 1940
Prinzenerlass decree. From the early 1930s he served as Prince-Grand Prior of the
Order of Saint Lazarus in Germany. ==Marriage and children==