The Lost Cause of the Confederacy is an American pseudohistorical and historical negationist myth that claims the cause of the Confederate States during the American Civil War was just, heroic, and not centered on slavery. First enunciated in 1866, it has continued to influence racism, gender roles, and religious attitudes in the Southern United States into the 21st century. Historians have dismantled many parts of the Lost Cause mythos.

Pseudohistory is a form of pseudoscholarship that attempts to distort or misrepresent the historical record, often by employing methods resembling those used in scholarly historical research. The related term cryptohistory is applied to pseudohistory derived from the superstitions intrinsic to occultism. Pseudohistory is related to pseudoscience and pseudoarchaeology, and usage of the terms may occasionally overlap. Although pseudohistory comes in many forms, scholars have identified many features that tend to be common in pseudohistorical works; one example is that the use of pseudohistory is almost always motivated by a contemporary political, religious, or personal agenda. Pseudohistory also frequently presents sensational claims or a big lie about historical facts which would require unwarranted revision of the historical record.