Schnabel was born in Mannheim as the son of the merchant Karl Schnabel and his wife Maria Anna, née Guillemin. Schnabel's parents - the father, a Protestant, the mother a Catholic - had married in 1885 and raised their three children n the Roman Catholic Church faith: the second born Franz had an older and a younger sister. Schnabel grew in the milieu of liberalism in Baden. The bourgeoisie of his native city and, looking back, the close relationship to France that existed through his mother's family, had a formative influence on his personal development: "Thanks to my mother's relatives I came to Normandy and Paris as a boy. But whoever treads French soil in his youth will always take with him a sense of the great contours of world history".Aus dem Nachlass zitiert bei Heinrich Lutz: Einleitung. In Franz Schnabel: Abhandlungen und Vorträge 1914–1965. Edited by Heinrich Lutz. Freiburg/Basel/Vienna 1970, , here Anm. 8. Schnabel attended the from which he graduated in 1906. He then studied History, German studies, French and Latin at the Humboldt University of Berlin and the Ruprecht-Karls-University Heidelberg. In 1910, he passed the Staatsexamen for the teaching profession at grammar schools and was awarded his doctorate in the same year under Hermann Oncken with the thesis The Unification of Political Catholicism in Germany in 1848.Thomas Hertfelder: Franz Schnabel. In Katharina Weigand (ed.): Münchner Historiker zwischen Politik und Wissenschaft. 150 Jahre Historisches Seminar der Ludwig-Maximilians-Universität. Munich 2010, , here .
