In recent decades, alternatives to the established bubonic-plague theory have been presented as to the microbiologcal identity and mechanism(s) of spread of historical plague epidemics. In What Disease was Plague?, the six important alternative theories are intensively discussed in the light of the historical sources, the central primary studies and standard works on bubonic plague and the alternative microbiological agents, insofar as they are testable. These seven theories are incompatible and at least six of them must be untenable. In the author's opinion, the arguments against the bubonic-plague theory and for all alternative theories are untenable. What Disease was Plague? therefore also has been written also as a standard work on bubonic plague, giving a broad and in-depth presentation of the medical, epidemiological and historical evidence and the methodological tenets for identification of historical diseases by comparison with modern medical knowledge.
Ole J. Benedictow, Cand. Philol. in History (1961), University of Oslo, Emeritus Professor of History at the University of Oslo. He has published extensively on historical plague epidemics and medieval demography including The Black Death 1346-1353: The Complete History (Boydell & Brewer 2004), The Black Death and Later Plague Epidemics in Norway (in Norwegian, Unipub 2002), and The Medieval Demographic System of the Nordic Countries (Middelalderforlaget, 2nd ed. 1996).