The complex story of how the war to preserve the Union evolved into a war to give that Union "a new birth of freedom" has been told many times--but never so well as Allen Guelzo tells it in Lincoln's Emancipation Proclamation. Once considered Lincoln's greatest achievement, the proclamation's reputation has declined in recent decades. Citing its dry legalistic language, the eminent historian Richard Hofstadter famously declared that the proclamation "had all the moral grandeur of a bill of lading." By limiting its application to states or parts of states under Confederate control, critics assert, Lincoln's proclamation freed no flesh-and-blood slaves and left those in areas controlled by the Union forces still in slavery. Real emancipation, insist many African-American historians, was accomplished by the slaves themselves. By running away and entering Union lines during the war, they not only liberated their own persons but also forced the issue of emancipation on a laggard Lincoln. "Freedom did not come to the slaves from words on paper," writes the Columbia University historian Barbara Fields, but "from the initiative of the slaves." And the institution of slavery came to an end with the Thirteenth Amendment in 1865, not with the Emancipation Proclamation in 1863.
Conceding the partial validity of these critiques, Guelzo painstakingly disentangles truth from distortion and error. The proclamation's language was dry and technical because it was framed by a lawyer/President who wanted to make it as legally airtight and politically inoffensive as possible at a time when a large part of the Northern population opposed emancipation. The proclamation applied only to areas in rebellion because its legal basis was the President's war power as Commander in Chief to seize enemy property being used to wage war against the United States. Even if little of this property was instantly liberated on January 1, 1863, the proclamation constituted a promise that it would be carried out by advancing Union armies. As Lincoln said many times thereafter, "the promise being made, must be kept." The physical achievement of freedom did indeed occur when slaves came within Union lines. But it also happened when the armies moved into areas where slaves lived. Guelzo persuasively maintains that, by making freedom an official policy, the proclamation produced a quantum leap in the number of slaves seeking that freedom. Word of Lincoln's edict spread widely by the slaves' "grapevine telegraph" and "triggered a cascade of running away in 1863 that began sweeping off the underpinnings of slavery."
Lincoln understood better than anyone else that the proclamation was a war measure that would cease to operate when the war was over. He also worried that the courts might invalidate it retroactively on the grounds that the Commander in Chief could seize enemy property but could not permanently free slave property. Lincoln's preferred method for ending slavery was by the constitutional actions of the slave states themselves. In 1862 he tried to persuade the loyal border states to take such action, hoping that a domino effect might topple slavery state by state until all were free. The border states refused. Lincoln moved beyond them to issue the proclamation, and in 1864 he ran for re-election on a platform promising a constitutional amendment to end slavery everywhere. Lincoln called the Thirteenth Amendment a "King's cure" that "alone can meet and cover all cavils." The Emancipation Proclamation was the single most important step in the journey to that King's cure. Guelzo concludes that even if the Emancipation Proclamation was "not...the most eloquent of Lincoln's writings, it was unquestionably the most epochal," and that even if Lincoln was not "the most perfect friend black Americans have ever had," he manifestly "was the most significant."