He also said that if he could "preserve the Union" by freeing all the slaves, he would do so.
Which is irrelevant to the point that Lincoln was not fighting a war to end slavery, but was instead fighting a war to end independence from Washington D.C.
IOW, it wasn’t ever about freeing the slaves. Whether they got freed or not was inconsequential. What it was about was preserving the Union (by force.) If the slaves stayed slaves, OK. If they all got freed, OK. Whatever served the interest of preserving and expanding the power of DC.
All in the name of liberty, of course.