Leonida Tonelli: a biography

This paper aims at going through the work by Leonida Tonelli, with a focus on the results he got in the fields of Real Analysis and Calculus of Variations, and put it within the socio-political context of his time. One of the most outstanding Italian analysts in the first half of twentieth century, first in Bologna and then in Pisa and Rome, Leonida Tonelli’s path combined elements of different, conflictual in some moment, relationships which featured at that time Italian mathematics and which linked the latter with Giovanni Gentile, the Fascism and the after-war “new” Italy.