Following the annexation of South Tyrol by Italy a law was enacted which made it possible to emigrate to Austria within one year while retaining Austrian citizenship. Those who did not do this, virutally everyone, was thenceforth an Italian citizen. As Italian citizens, male South Tyroleans were subject to conscription. Thus they had to serve in the army and also participated in conflicts such as the war in Abessinia(Ethiopia) and in the Spanish Civil War.

In the years leading up to the Second World War one of the main goals of Nazi Germany was the "bringing home into the Reich" of German peoples living outside of Germanies borders. Even though Hitler had already stated that an alliance with Italy was more important to him than the German South Tyroleans, a pro nazi movment formed in South Tyrol. When Austria was annexed by Germany many South Tyroleans were sure that "their" Führer would also liberate them soon. To ease relations between the two countries and because Mussolini was interested in a German free South Tyrol and Hitler in those Germans, the so called "Option" came about. Every German family had to decide until 31 December 1939 if it wanted to remain in South Tyrol and retain Italian citizenship or become German and emigrate to Germany. 166,448 decided for Germany and 63,012 for Italy.

Along with opting for Germany about 2,000 men also volunteered to join the Germany Army, both the Wehrmacht and the Waffen-SS. In hope of a better future standing inside of Germany and maybe even a regaining of South Tyrol after the war pro-German groups encouraged joining the Waffen-SS, because it would provide more political influence. In May 1940 South Tyrol had the second highest proportion of Waffen-SS recruits to total population of all German groups, only behind the Baltic Germans.

Those who actually emigrated to the German Empire during the war, less than 80,000, were subject to conscription there as German citizens. Meanwhile those who opted for Germany but had not emigrated yet could not be conscripted into the Italian Army because they were now German citizens. Those serving who decided for Germany and were currently serving in the Italian Army were transfered into the German Army.

While enthusiasm for the war had initially been big this diminshed over time and many tried to stay in Italy so they would not be conscripted. This led to an agreement between Hitler and Mussolini in August 1941 which made it possible for Germany to conscript those who had opted for Germany but still remained in Italy.

Finally after Italy concluded an armistice with the Allies in September 1943 and Mussolini established the Italian Social Republic in Northern Italy, South Tyrol was occupied by the Germans. This removed the previous barriers to concripting the remainers and from 1944 it was even expanded to those who had decided to become Italian citizens.

South Tyroleans showed a preference to joining mountaineer units, both in the Wehrmacht and in the Waffen-SS. After fighting broke out in Italy they were also often used there, to ease cooperation with Italian troops.

All in all more than 20,000 South Tyroleans served in the German Armed Forces during the Second World War. According to German statistics there were about 250,000 Germans in the province in 1939, of whom 105,000 were male.