"The cyclorama re-created the Battle of Gettysburg in stunning realism, with impeccable attention to the smallest minutiae. Yet it offered not a single clue as to why the battle had been fought. No matter how hard they looked, or how long they stared, no visitor would find in the painting any trace of the cause of the war. There was carnage. There was valor. But there was no purpose."
Yoni Applebaum at The Atlantic depicts the history of the Gettysburg Cyclorama.