Short answers, pulled from the story.
The Lost Cause of the Confederacy is an American pseudohistorical myth, first articulated in 1866, that argues the Confederate States' goals during the Civil War were morally just and not centered on maintaining slavery. It claims that states' rights, not slavery, caused the war, portrays Confederate leaders as heroic and saintly figures, and characterizes enslaved African Americans as contented with their condition.
The term was popularized by Virginian journalist Edward A. Pollard in his 1866 book The Lost Cause: A New Southern History of the War of the Confederates. According to Pollard, the title was inserted at his New York publisher's request, who feared the original title, History of the War, would not sell.
The United Daughters of the Confederacy was the primary organization behind Lost Cause monuments, textbooks, and educational campaigns for over a century. The UDC controlled the writing and adoption of history textbooks in Southern schools, funded Confederate descendants to attend college and then teach Lost Cause ideology, erected monuments including a loyal slave memorial at Arlington National Cemetery in 1914, and supported the Ku Klux Klan, with members publishing books and primers celebrating the Klan as saviors of the South.
The Lost Cause reached its first peak of popularity at the turn of the 20th century, when Confederate veterans were dying and organizations rushed to memorialize them. It reached a second high point during the civil rights movement of the 1950s and 1960s, when new monuments were erected as a direct response to growing public support for racial equality.
Frederick Douglass wrote in 1870 that monuments to the Lost Cause would prove "monuments of folly" and on the 30th of May 1871, delivered a speech at Arlington National Cemetery insisting that those who fought for slavery and those who fought for liberty could not be equally honored. W. E. B. Du Bois wrote in 1931 in The Crisis, the NAACP's official magazine, that the truthful inscription on Civil War monuments would read "sacred to the memory of those who fought to Perpetuate Human Slavery".
The UDC and the United Confederate Veterans succeeded by 1910 in making Lost Cause literature dominant in American classrooms. Northern publishers produced separate Lost Cause editions of history books for Southern markets to retain state contracts, and those narratives spread northward over time. Until the 2019-2020 school year, Texas required teaching that slavery was the third cause of the Civil War behind states' rights and sectionalism.