Disclaimer: This answer is in my own words, and it is also my own opinion. But I hope this helps you!
The Emancipation Proclamation of 1863 and the Gettysburg Address of 1863 didn't exactly change the purpose, or output of the American Civil War. It's known that the Emancipation Proclamation didn't truly free all slaves; rather, it freed those who weren't under Union control. The American Civil War rooted from slavery, and the status of African American citizens. As we've seen, despise his best efforts, Lincoln's speeches didn't change the fact that slavery was still happening. Therefore, this makes the speeches seem null and void - nothing more than empty gestures, and empty promises for a better future.
Again, this is my opinion, feel free to tweak this in any way you want.