[3] At the outbreak of the First World War, Wagner abandoned his studies (which he never finished) and became a one-year volunteer in the Imperial German Army.

After being wounded and hospitalized in July 1915, he attended Reserve Officer Candidate Training courses and was commissioned as a Leutnant in February 1916.

Assigned as a platoon leader with the 110th Reserve Regiment from July 1916 through the end of the war, he was again wounded in a poison gas attack in June 1917.

[4] In February 1919, Wagner joined the 2nd Baden Volunteer Battalion, with whom he participated in the suppression of revolutionary unrest in Mannheim and Karlsruhe.

[5] The reason for the name change from his father's (Backfisch, which means "teenage girl" (literally "fried fish")) was probably to avoid teasing by his fellow officers.

In September 1923, by now an Oberleutnant, he was posted to the Central School of Infantry in Munich, then the principal officer training facility in Germany.

From December 1932 through March 1933 he was temporarily transferred to the Party headquarters at the Brown House, Munich as Deputy to Robert Ley and head of the Hauptpersonalamt (Main Personnel Office).

Turning over the premiership to Walter Köhler, on 5 May he assumed the new, more powerful position of Reichsstatthalter (Reich Governor) of Baden, thus uniting under his control the highest party and governmental offices in his jurisdiction.

[10] Shortly after the outbreak of the Second World War, Wagner was named to the Defense Committees of Wehrkreise (Military Districts) V and XII, in which parts of his Gau were located.

After the fall of France, Germany incorporated Alsace (Elsaß) into the Greater German Reich and on 2 August 1940 Wagner became Chief of Civil Administration for the region.

Wagner immediately embarked on an aggressive Germanization campaign in Alsace, vowing to achieve this goal in half the time.

[11] On 25 August 1942, Wagner issued a decree ordering the conscription into the Wehrmacht on all Alsatian men of military service age.

In February 1943, Wagner ordered the execution of 12 men from Ballersdorf who tried to avoid compulsory military duty by attempting to cross into nearby Switzerland.

[citation needed] The Jews expelled from both Baden and Alsace were housed under cruel conditions in the Gurs internment camp at the foot of the Pyrenees.

Following the scorched earth policy detailed in Hitler's Nero Decree, he ordered cities in Baden to destroy their infrastructure to hinder the advance of the Allies.