[1] Wahl served in the First World War on the western front as a Sanitäter (combat medic) with the 5th Royal Bavarian Field Artillery Regiment and was seriously wounded with grenade fragments to the knee on 12 October 1914, being hospitalized until March 1915.

Hospitalized with influenza at the end of the war, he returned to Germany and remained in the military, posted in Augsburg, until being discharged in November 1921.

Settling in Augsburg, he completed his education at a Volkshochschule and entered the civil service, working as an assistant to the director of the city slaughterhouse until 1927.

When the Party was banned in the wake of the Beer Hall Putsch, Wahl joined the Völkisch-Social Bloc, another right-wing group closely aligned with the Nazis.

Additionally, Wahl was appointed to the office of Acting Regierungspräsident (District President) of Swabia on 10 April 1934 (made permanent on 1 July 1934).

[9] Wahl joined the SS with the rank of honorary SS-Gruppenführer on 9 September 1934 and was assigned to SS-Oberabschnitt-Süd (Senior District-South) in Munich until 1 April 1936 when he was reassigned to the staff of Reichsführer-SS Heinrich Himmler.

[6] In his time as Gauleiter, Wahl, raised a Protestant but married to a Roman Catholic, enjoyed good relations with the church, something not appreciated within the higher party ranks, especially by Himmler and Bormann.

[13] In May 1941, he gave a rather telling speech at the Messerschmitt factory, voicing his belief in Hitler and his mission from God to punish all people and countries which have strayed from the path of decency.

He denounced the leaders of many of the countries Germany had defeated as cowards, due to the fact that they fled to England and elsewhere rather than stayed or died with their people and soldiers.

Hitler issued on this occasion in front of a large number of Gauleiter the statement that "the German people did not have the inner strength they were perceived to have" and therefore were losing the war.

With the worsening war situation in April 1945, Wahl was subordinated militarily to Paul Giesler, the Gauleiter of neighboring Gau Munich-Upper Bavaria who now was also placed in charge of Swabia and three Austrian Gaue as “Reich Defense Commissioner South.”[19] In the last days of the war, unlike many of his fellow Gauleiters, Wahl did not flee or commit suicide.

[20] Wahl was subsequently held in 13 different internment camps and prisons over the next few years, including Dachau and appeared as a witness at the Nuremberg trials in 1946.

[25] His grave in Augsburg-Göggingen, where he is buried together with his wife, carries the message: "Do not tire of doing good deeds" (German: Werdet nicht müde das Gute zu tun).

He states that he was approached by soldiers of the Wehrmacht, returning on front leave to Swabia, who told him of the extermination of Jewish people in Eastern Europe.

[5] In The End, Ian Kershaw describes him as "one of the less extreme of the Gauleiter" who in spite of his seniority (via early party membership) "did not stand high in the esteem of Hitler and Bormann" and contrasts Wahl's relative apathy towards the regime's exhortations to fight to the last man with the well-documented fanaticism and cruelty of several other Gauleiters.

Kershaw points out, however, that Wahl did advocate to Bormann the use of kamikaze-like suicide attacks with bomb-laden aircraft on US supply bridges over the Rhine.

Kershaw posits that Wahl could have made such a suggestion as a means of affirming loyalty to the regime in its final months, when reprisals against defeatist sentiment were at their height.