The History of the Decline & Fall of the Roman Empire was written by English historian Edward Gibbon and originally published in six quarto volumes. Volume 1 was published in 1776, going through six printings; volumes 2-3 in 1781; and volumes 4-6 in 1788-89. It was a major literary achievement of the 18th century, adopted as a model for the methodologies of historians.

The books cover the Roman Empire after Marcus Aurelius, from 180 to 1590. They delve into the behavior and decisions that led to the eventual fall of the Empire in both the East and West, offering explanations. Gibbon is called the first modern historian of ancient Rome due to his objective approach and accurate use of reference material, setting a standard for 19th and 20th-century historians.

His work is characterized by pessimism and detached irony, common to the historical genre of his era. Although he published other books, Gibbon devoted much of his life (1772-89) to this one work. His Memoirs of My Life & Writings reflect on how this book virtually became his life.

Gibbon offers explanations for why the Roman Empire fell, a task made difficult by the scarcity of comprehensive written sources. According to Gibbon, the Empire succumbed to barbarian invasions due to the loss of civic virtue. They had become weak, outsourcing defense to barbarian mercenaries who eventually took over. Romans had become effeminate, incapable of maintaining a tough military lifestyle. Additionally, Christianity fostered a belief in a better life after death, sapping patriotism and martial spirit. Like other Enlightenment thinkers, Gibbon held the Middle Ages in contempt as a superstitious, priest-ridden dark age, believing only the age of reason could progress history.