Was the union for slavery or against slavery?

Answer 1

The union was against slavery.

There were slave states within the Union however the South was more pro slavery. The issue of slavery had been building for years prior. One of the major arguments was whether or not slavery would be allowed in the west. And it was the election of Lincoln, well known for his opposition of slavery, which prompted South Carolina to attempt secession in 1860.

Southern apologists and historical revisionists often say that the war was about "states rights" and partly this is true but the Constitution of the Confederate States of America, as they called themselves, was almost identical to the U.S. Constitution except that it gave legal protection to the institution of slavery so however important "states rights" or "limited federal government" was to the south, it was certainly not as important as slavery.

The fact is, much of the north was fiercely abolitionist. Many of the popular songs of the north recanted the evils of slavery and hope of freedom for the slaves in the south. And with the Emancipation Proclamation Lincoln not only prevented any European aid for the south - as almost all of Europe was currently waging its own war against slavery - but swelled the Grand Army of the Republics ranks with thousands of new abolitionist volunteers.