The History of the Norman Conquest of England: Its Causes and Its Results (1867–1879) is a six-volume study of the Conquest by Edward A. Freeman. Recognised by critics as a major work of scholarship on its first publication, it has since proved unpopular with readers, many of whom were put off by its enormous length and copious detail. Academics have often criticized it for its heavily Whig treatment of the subject, and its glorification of Anglo-Saxon political and social institutions at the expense of their feudal successors, but its influence has nevertheless been profound, many Anglo-Norman historians of modern times having come around to some of Freeman's main conclusions.
Freeman first wrote about the Conquest while he was still a student at Oxford, where his 1846 essay "The Effects of the Conquest of England by the Normans" was submitted for, but failed to win, a prize. In 1859 and 1865 he published lengthy reviews of the last two volumes of Sir Francis Palgrave's History of Normandy and of England. Exploring his points of agreement and disagreement with Palgrave Freeman decided to embark on his own history of the Conquest, reasoning that its approaching 800th anniversary might well make such a work popular. He believed that he had so completely worked out his own position on the historical controversies involved that "there will be little more to do than write down what is already in my head". He began work on the History on 7 December 1865, writing to a friend that it was a book "which I can do easier than anybody else, as I have worked so much at the subject for twenty years past". In the event, Freeman's decision to trace the remoter causes of the Conquest in much greater detail than he had originally planned put paid to all hopes of bringing his history down to William the Conqueror's accession in time for the octocentenary. His first volume, taking the story as far as the death of Harthacnut, appeared in 1867; subsequent volumes in 1868, 1869 and 1871 dealt with the reigns of Edward the Confessor, Harold Godwinson and William the Conqueror respectively; and an 1876 volume explored the consequences of the Conquest in later reigns, with a final index volume in 1879. Freeman later issued two revised editions.