Between 1915 and 1918, Holz served in a number of units: Reserve-Infanterie-Regiment 16, Infanterie-Regiment 144, Infanterie-Regiment 179, and Jager-Bataillon 24 on the Western Front. He sustained a number of wounds. He returned to Nurnberg in September, 1919 and took a job as an official in Nuremberg. In 1920 he joined the German Socialist Party (Deutschsozialistische Partei). Once its chairman Julius Streicher had gone over to the Nazis in 1922, the party was melded into the NSDAP. Holz officially joined the Nazis on 11 November 1922 and his membership number was 77. Holz joined the Sturmabteilung and stayed until 1933 with the rank of Sturmführer.
Quite early on, Holz established a close relationship with Streicher. In 1924, Holz was elected to Nuremberg City Council, which he quit the following year. Between 1927 and 1933, he held the post of editor-in-chief of Der Stürmer, Streicher's anti-Semitic weekly newspaper. In 1933 he was given the position of ministerial adviser.
As of 1 January 1934, Holz operated as Streicher's representative in his capacity as Gauleiter of Franconia. In July 1934, Holz was appointed NSDAP Kreis leader of Nuremberg-town, and in November came his promotion to SA Brigadeführer.
In 1940, in connection with the Streicher irregularities involving the Aryanization of Jewish assets, Holz was temporarily stripped of all his offices. Appointed Reich Defence Commissar of Franconia as of November 1942, he was furthermore assigned the Gau leadership on 8 March 1943. Although Streicher was still Gauleiter, Adolf Hitler appointed Holz as such in November 1944.
After American troops of the 3d Infantry Division had all but taken Nuremberg on 18 April 1945, Holz barricaded himself in the Palmenhofbunker at the Nuremberg Police Presidium along with a small group, among whom was the city's mayor, Willy Liebel. It has been assumed that Holz shot Liebel in the Palmenhofbunker owing to the latter's efforts to surrender the city to put a stop to the fighting, and because there had been a rivalry between the two men for years over who should have the power within the local Nuremberg NSDAP. Holz met his own end in the same place on 20 April – coincidentally Hitler's birthday – but whether it was suicide or an injury sustained in the battle is unknown.
Every bit as unsqueamish as his predecessor as Gauleiter, Julius Streicher, Holz boasted many penalties for political crimes (by his own count 17, and among those 5 prison sentences). With his aggressive way of doing things, even dissenters within the party had to suffer with the knowledge that Holz, as a party man and as Streicher's pupil, had partly taken over from his master. The Gauleiter's office in Upper Franconia, which was already much striven-after even before the Nazis seized power, was successfully disputed by the BayreuthKreisleiterHans Schemm, despite Streicher's support for Holz.
Miller, Michael D. and Schulz, Andreas (2012). Gauleiter: The Regional Leaders of the Nazi Party and Their Deputies, 1925-1945 (Herbert Albreacht-H. Wilhelm Huttmann)-Volume 1, R. James Bender Publishing. ISBN 978-1932970210