In 1860, the institution of slavery was firmly entrenched in the United States; by 1865, it was dead. How did this happen? How did Union policy toward slavery and enslaved people change over the course of the war? Why did it change?

The change in slavery started in November 1860 with the Republican victory in the elections, an immediate danger to the slave owning republic in existence since 1776. The Republican Party and Lincoln – who did not win a single vote in the South, vowed to prevent the extension of slavery. To save the black slavery and the supremacy of white men, radical Southerners chose secession, while Northerners believed that the collapse of
Union will destroy the possibility of a democratic republican government. This resulted in the Civil War, finally leading to the end of slavery in the United States. Antislavery Republicans asked that the goal of the war should be abolition of slavery and restoration of the Union; the war should continue “until the Slave power is completely subjugated, and emancipation made certain.” Lincoln first rejected emancipation as a goal of the war;  he never thought of putting an end to slavery. But numerous slave escapes in the South burdened the president. The Union’s fate was at stake and Lincoln’s major commitment was to save the Union. “If I could save the Union without freeing any slave, I would do it,” the president stated, “and if I could save it by freeing all the slaves, I would do it.” In the light of these events, Lincoln finally surrendered to the pressure of antislavery republicans, making the Civil War to mainly be about slavery, and seeing the abolition as a way to end the rebellion and preserve the Union. The president drafted a general proclamation of emancipation in July 1862, laying the foundation for the destruction of slavery. The proclamation was issued on September 22, basing its legal authority on his responsibility to suppress the rebellion and was signed by Lincoln on January 1, 1863. Right after the war, abolitionists were worried that the Emancipation Proclamation, being based on the Lincoln’s wartime powers, would lose its force post bellum. Pushed by the president and the National Equal Rights League, on January 1865 the Congress approved the Thirteenth Amendment, ending slavery, and sent it to the states for ratification.

Sources:

Henretta, James A, and David Brody, America: A Concise History, Volume I: To
1877. 4th ed., Boston: Bedford/ St. Martin’s, 2010, 407-431

Slavery In The Civil War Era, 08/26/2010, http://www.civilwarhome.com/slavery.htm