Involvement with the NSDAP
While in Italy, Philipp fell under the influence of Fascism, or otherwise believed the Bolsheviks to be a greater threat. On his return to Germany in October 1930, he joined the National Socialist German Workers' Party. He was assigned Party membership number 418,991 and, on 30 January 1939, he would be awarded the Golden Party Badge. On 1 July 1932, he joined the Stormtroopers (SA, commonly referred to as the brownshirts) with the rank of SA-Oberführer. He was promoted to SA-Gruppenführer on 13 May 1933 and SA-Obergruppenführer on 9 November 1938. In 1933, his younger brother Christoph joined the Schutzstaffel (SS). Later, his two other brothers, including Wolfgang, also joined the SA. Through his party membership, Philipp became a particularly close friend of Hermann Göring, the future head of the German Air Force (Luftwaffe). Göring would bestow the rank of Luftwaffe Hauptmann of reserves on Philipp in 1936.
Following the appointment of Adolf Hitler as the German Chancellor on 30 January 1933, Philipp was appointed Oberpräsident (Governor) of Hesse-Nassau on 7 June 1933 by Prussian Minister-President Göring, who also named him to the Prussian State Council in July. Philipp played an important role in the consolidation of National Socialist rule in Germany. He introduced other aristocrats to NSDAP officials and, as son-in-law of the king of Italy, was a frequent go-between for Hitler and Benito Mussolini. He also acted as an art agent for Hitler in Italy. Philipp arranged the purchase of many important works of art for the large museum that Hitler was planning in Linz. For this purpose, the Reich Chancellery established a special account for him at the German Embassy in Rome, over which Prince Philipp could freely dispose. In 1940/41, German art purchases in Italy increased to such an extent that the Fascist government prohibited the sale of art treasures to foreigners in September 1941. On 11 March 1938, he delivered Hitler's letter of reassurance to Mussolini prior to Hitler's marching into Austria, and received a gushing call from Hitler upon the news of Mussolini's acquiescence.
As governor of Hesse-Nassau, Philipp was associated with the Aktion T4 euthanasia programme. In February 1941, Philipp signed the contract placing the sanitarium of Hadamar Clinic at the disposal of the Reich Interior Ministry. Over 10,000 mentally ill people were killed there. In 1946, Philipp was charged with murder, but the charges were later dropped.
As the war progressed, the attitude of the National Socialist authorities towards members of the German princely houses changed. While at first, they had been happy to use the historic family names to bolster popular support, they now decided to distance themselves even from those princes who had supported them.
In late April 1943, Philipp was ordered to report to Hitler's headquarters, where he stayed for most of the next four months. In May 1943, Hitler issued the "Decree Concerning Internationally Connected Men" declaring that princes could not hold positions in the party, state, or armed forces. The arrest of Mussolini by Philipp's father-in-law King Victor Emmanuel in July 1943 made Phillipp's position even more difficult.
