What is the summary of the Emancipation Proclamation in one paragraph?

Despite his personal opposition to slavery, when President Abraham Lincoln took office in 1861 he insisted that his constitutional duty was to keep the nation together, not to abolish slavery. He conducted the first year of the war with the goal of reuniting the Union, but wartime events, including heavy military losses and the many slaves who escaped behind Union battle lines, forced him to contend with the issue of slavery. He issued a preliminary Emancipation Proclamation on September 22, 1862 and the final version on January 1, 1863, fundamentally changing the meaning of the war.