Cavour and Garibaldi, 1860: A Study in Political Conflict, 1954.
Garibaldi: A Great Life in Brief, 1956.
Italy: A Modern History, 1958, revised 1969, completely revised and reprinted as Modern Italy: A Political History, 1997.
A History of Sicily, with Moses Finley, in two volumes, Medieval Sicily 800-1713 and Modern Sicily after 1713, 1968; abridged and reprinted as the single volume A History of Sicily with Moses Finley and Christopher Duggan, 1986.
The Making of Italy, 1796-1870, 1968 (editor), reprinted as The Making of Italy, 1796-1866, 1988.
Great Lives Observed: Garibaldi, 1969 (editor).
Victor Emanuel, Cavour and the Risorgimento, 1971.
Vittorio Emanuele II, 1975.
Mussolini's Roman Empire (Le guerre del Duce), 1976.