Louis P. Masur is the author of Lincoln's Hundred Days: The Emancipation Proclamation and the War for the Union. He is a professor of American studies and history at Rutgers University.

William Lloyd Garrison, the fiery abolitionist editor of the Liberator, had struggled for decades to see slavery abolished, but when Abraham Lincoln issued the preliminary Emancipation Proclamation on September 22, 1862, the long-awaited action came as a disappointment. Garrison was furious. Lincoln’s decree would free the slaves in rebel-controlled areas in the seceded states on January 1, 1863, a hundred days away. The delay was intended to give the Confederate states a chance to return to the Union and thus prevent the proclamation from applying to them. Lincoln also believed that the public needed time to digest this unprecedented development. “The President can do nothing for freedom in a direct manner, but only by circumlocution and delay,” lamented Garrison, who on an earlier occasion declared, “If he is 6 feet 4 inches high, he is only a dwarf in mind.”

What was taking Lincoln so long? Did he not understand that slavery caused the rebellion and that to end it he must immediately attack the institution? In a speech delivered on October 1, 1861, nearly a year before the preliminary Emancipation Proclamation, U.S. Senator Charles Sumner had thundered, “It is often said that war will make an end of Slavery. This is probable. But it is surer still that the overthrow of Slavery will at once make an end of the war.” Sumner kept steady pressure on the president, visiting the White House not once but twice on July 4, 1862, to implore Lincoln to sanctify the day by emancipating the slaves. Yet Lincoln did nothing more than try to placate Sumner—the Massachusetts senator, he said, was only a month or six weeks ahead of him in his thinking.

The timing of the final proclamation was part of the withering criticism it faced, and the decree has never fully escaped allegations cast by commentators across the political spectrum: that it was unconstitutional, that it could not be enforced, that it would lead to racial warfare, and that it hardly liberated anyone. The soulless language of the document has seemed especially galling to some. In 1948, Columbia historian Richard Hofstadter quipped that the Emancipation Proclamation had “all the moral grandeur of a bill of lading,” and the censure has stuck. In recent decades, a shift in scholarly focus to those outside traditional channels of power suggested that Lincoln did not free the slaves, but rather, the slaves, by running away, freed themselves. Lincoln the emancipator was reduced to Lincoln the procrastinator.

It is lamentable that we have distanced ourselves from the proclamation and have allowed it to be diminished by criticisms of its timing, prose, and perceived efficacy. Lincoln was a cautious politician, and he would not be pressured. He once told the story of a man with a mill, located at the top of a hill, whose water supply came from a lake. The man “opened the sluice a trifle & the water rushed out, widening the passage until its volume swept off mill & miller.” If not handled with care, emancipation could have been the torrent that drowned one and all. Lincoln took every precaution to make certain that would not happen; freedom hurried could be freedom lost. His deliberate decision making may have driven radicals to despair, but it assured the triumph of the final Emancipation Proclamation....