Few diseases are extensively diffused as influenza, but though flu pandemics occur with regularity throughout history the bibliography is dominated by the 1918-1919 “Spanish influenza” pandemic. This review argues that this preoccupation is largely a product of historical epidemiology and retrospective statistical analysis which has made the Spanish flu the reference point against which other modern respiratory pandemics, including COVID-19, are measured—hence the Spanish flu’s importance for the 21st century pandemic imaginary. The review identifies six distinct thematic areas within the (...) historiography of H1N1 Spanish influenza. These include medical writings which attempt to read the history of the Spanish flu backwards to “learn” public health “lessons” for the mitigation of future pandemics, and ecological writings in which influenza is seen as the paradigm of an emerging infectious disease and a model for the genesis of epidemics and pandemics from zoonotic reservoirs. Scholarship since 1997 also reflects a growing interdisciplinarity, one in which bioarchaeology and molecular dating techniques have furnished new insights into the history of influenza and the Spanish flu’s evolutionary origins, bringing the life sciences into closer dialogue with the medical and environmental humanities. These scientific insights have spurred both academic and popular writings on the Spanish flu, rendering its characterization as the “forgotten pandemic” something of an oxymoron. Indeed, if anything, the centenary of the Spanish flu in 2018 and the 2019-2023 COVID pandemic have provoked renewed interest in several of the themes identified in this review: including, most particularly, the writings of social historians of medicine, cultural historians, and disease demographers. (shrink)