Many of Fichtenau's books were translated into English and he remains one of the few Austrian medievalists of the postwar period whose work has enjoyed a broad and influential reception in Anglophone scholarship.
[1] He subsequently continued on for his doctoral degree, awarded in 1940, under the Institute's director Hans Hirsch, and wrote his Habilitation thesis while serving on the Eastern Front in the German Wehrmacht during World War II.
Written in post-war Vienna, the book was a frank, if understandably cynical, take on historical narratives of the early Middle Ages which celebrated power, conquest, and the idealized image of a pan-European polity.
Fichtenau was appointed Extraordinary (Associate) Professor of History at Vienna in 1950, and received a promotion to a full professorial chair (Ordinarius) in 1963, at which time he also assumed the director's position at the Institute.
In a series of studies entitled Arenga: Spätantike und Mittelalter im Spiegel von Urkundenformeln (Cologne & Vienna, 1957), Fichtenau traced shifts in the self-representation of medieval rulers in the rhetoric of the introductory clauses of their diplomas.