Lincoln released his lesser-known preliminary Emancipation Proclamation on Sept. 22, 1862. That was 100 days before the final version. The first of the two documents has gained importance among historians as a turning point in the Civil War.
Edward Ayers is a historian and president of the University of Richmond. He says slavery and its abolition were once treated as minor parts of the Civil War, but that began to change after the Civil Rights movement.
The official government copy of the preliminary proclamation goes on display in New York on Saturday, while other commemorations of emancipation kicked off earlier this week.