As Professor Mazzie has noted, today, November 19, 2013—the day that I am writing this—is the 150th anniversary of Abraham Lincoln’s brief but iconic Gettysburg Address. Rereading its text earlier today, I was reminded how committed the speech was to the cause of emancipation. Although most of the Union dead at Gettysburg were there to save the Union, not to abolish slavery, it was clear that the emancipation of African-American slaves was very much on Lincoln’s mind when he penned the famous words.

The references to slavery are admittedly somewhat oblique, and the word ‘slavery” is never used. However, the phrase “a new nation, conceived in Liberty, and dedicated to the proposition that all men are created equal,” which is prominently featured as the second half of the Address’ opening sentence, clearly refers to the famous, and then not yet fully realized, words of the slaveholder Thomas Jefferson’s Declaration of Independence. In the middle section of the work, Lincoln subtly indicates that the nation for which the Gettysburg dead made the final sacrifice was not the United States of 1860 reunited, but that unrealized nation of the Declaration, committed to liberty and equality.

Although the document famously ends with the hope that “that government of the people, by the people, for the people, shall not perish from the earth,” the more important phrase is the one that precedes it: “that this nation, under God, shall have a new birth of freedom” (emphasis added). The promise of the Gettysburg graveyard is not a reunited country, but a new country freed from slavery.

While it is true that Lincoln did not begin his term in office committed to the eradication of slavery, the events of the year and a half leading up to November 19, 1863, had transformed Lincoln from an opponent of the extension of slavery to a supporter of the eradication of the Peculiar Institution.

In April of 1862, Lincoln had convinced Congress to provide financial support to the four Union slave states (Missouri, Kentucky, Maryland, and Delaware) if they were willing to embrace gradual emancipation. The same month, Congress abolished slavery in the District of Columbia by compensating the slave owners and by offering support for those who were free to emigrate to the West Indies.

By mid-summer, he was already moving away from such modest anti-slavery gestures. In July, Lincoln informed his cabinet of his intention to issue an emancipation proclamation covering slaves in Confederate controlled areas once the Union achieved a significant military victory. Two month later, following the Battle of Antietam, he issued the preliminary Emancipation Proclamation (to take effect January 1, 1863). He again offered financial assistance to the Union slave states, but this time the funds could be used to facilitate either gradual or immediate emancipation.

No Confederate state surrendered in the final three months of 1862, so the Emancipation Proclamation took effect on January 1, and throughout the early months of 1863, the Union Army began to aggressively recruit black soldiers. African-American slaves in Missouri, Tennessee, and Maryland were giving the option of having their freedom purchased by the U.S. government, if they were willing to join the Union Army.

At the time that he delivered the Gettysburg Address in November, Lincoln had other plans underway to undermine slavery throughout the United States. On December 8, he issued his Proclamation of Amnesty and Reconstruction in which he offered amnesty to any Confederate who was willing to take an oath of loyalty to the United States, but only if he was willing to accept the emancipation of all slaves. In March, Arkansas unionists adopted a new state constitution, approved by Lincoln, which abolished slavery altogether. The following month, the Senate approved what would become the 13th Amendment.

Actual abolition of slavery throughout the United States would not come until December 1865, when the 13th Amendment became law, almost eight months after Lincoln’s assassination. However, as the Gettysburg Address revealed, by the end of 1863, Lincoln himself had begun to envision not just a reunited United States, but a new nation, freed once and for all of the curse of slavery.