In Daniel 9, Daniel read Jeremiah’s prophetic words and discovered that there was a set time for the captivity of his people to come to an end. But he needed the angel of the Lord to help him understand what he was reading and what actually needed to happen for the Jews to experience true liberation—in practice. Jeremiah had pronounced it, but it had not come to pass.
Similarly, the United States had lawfully pronounced the freedom of slaves in the 1862 Emancipation Proclamation. Still, it did not happen in practice—it was not fully enforced until two and a half years later, on June 19, 1865, in Galveston, Texas.