The "Lost Cause" was born pretty much immediately after the Civil War, in various Confederate memoirs - not least of which was Edward A. Pollard's The Lost Cause: A New Southern History of the War of the Confederates (1866) and Jefferson Davis' The Rise and Fall of the Confederate Government (1881), but the popular conception of the Lost Cause was born out by glorification of the rebels by groups like the United Daughters of the Confederacy (who raised Confederate memorials throughout the South) and Southern Historical Society, popular revisionist novels like Thomas F. Dixon, Jr.'s The Clansman: An Historical Romance of the Ku Klux Klan (1905) - which was later made into the film The Birth of a Nation (1915) - and the "Dunning school" of historiographical thought, whose members hyped the evils of Reconstruction and racist portrayals of freed blacks, sometimes recasting slavery as "not so bad." The "Dunning school" more or less starts with Reconstruction: Political & Economic, 1865–1877 (1905) by William Archibald Dunning, though it has several non-academic precursors.

Previous poster made some good points. The consensus is the case for "the lost cause" was established as a literary and cultural phenomenom by former confederate general Jubal Early. The Southern Historical Society published his works in the 1870s, which goes to the OP's question.