History of Italy
Duggan wrote books about Italian history. "A Concise History of Italy" (1994) allowed him to return to his original interest in medieval history. "The Force of Destiny: A History of Italy since 1796" (2007) focuses on Italy in the 19th and 20th centuries. "Francesco Crispi 1818–1901", the first biography in English on Prime Minister Francesco Crispi, explores Crispi's evolution from a revolutionary democrat to a bellicose authoritarian and his role in the unification of Italy. In his book "Fascist Voices" (2012), he used the diaries, memoirs and letters of thousands of ordinary Italian citizens to investigate why so many had closely identified with the early 20th-century fascist regime of Benito Mussolini.