He was eventually conscripted into the German Army as a lieutenant, and sent to the Eastern Front, where a severe injury lead to the amputation of his left leg.
In the postwar period Magnago started his political activities in the municipal council of Bolzano as a member of the newly founded South Tyrolean People's Party (SVP).
Under the new leader and new motto Los von Trient (i.e. away from Trento, with regard to the regional capital) the SVP started to take a harder line, in order to obtain a devolution of powers to the provincial level of administration.
His major political success was the commencement of the second Statute of Autonomy in 1972, which distinctly extended South Tyrol's legislative and executive competencies.
Due to his long-time commitment to self-governance of his native province, he is widely regarded as the father of South Tyrolean autonomy.