This submission has been removed because it is soapboxing, promoting a political agenda, or moralizing. We don't allow content that does these things because they are detrimental to unbiased and academic discussion of history.
The Union army did not go to war over slavery. The justification for the Civil War from the northern perspective was over the right of the southern states to secede. The southern states, however, seceded over the issue of slavery, as noted in their documents of secession:
"The people of Georgia having dissolved their political connection with the Government of the United States of America, present to their confederates and the world the causes which have led to the separation. For the last ten years we have had numerous and serious causes of complaint against our non-slave-holding confederate States with reference to the subject of African slavery."
The second paragraph of Mississippi's declaration is even more clear: "Our position is thoroughly identified with the institution of slavery-- the greatest material interest of the world. Its labor supplies the product which constitutes by far the largest and most important portions of commerce of the earth. These products are peculiar to the climate verging on the tropical regions, and by an imperious law of nature, none but the black race can bear exposure to the tropical sun. These products have become necessities of the world, and a blow at slavery is a blow at commerce and civilization. That blow has been long aimed at the institution, and was at the point of reaching its consummation. There was no choice left us but submission to the mandates of abolition, or a dissolution of the Union, whose principles had been subverted to work out our ruin."
The Emancipation Proclamation did not occur until January of 1863, nearly two years into the four year war. It should also be noted that there was no question of a "moral ground high enough to start a war over", as the first battle of the American Civil War was the Confederate General Beauregard firing on the Union troops stationed at Fort Sumter, so the Union did not actually start the war at all. The American Civil War was certainly fought over slavery, but it was not fought to free the slaves. Perhaps a subtle difference, but a significant one.