How was the Confederacy not a country? It SECEDED from the Union, and in case you don’t know what secede means here’s a definition- verb (used without object), se·ced·ed, se·ced·ing.
to withdraw formally from an alliance, federation, or association, as from a political union, a religious organization, etc.
They left from the Union and created a new nation, regardless of what the Northern historians say this is what happened, and to address the issue of slavery, the war wasn’t caused because the south wanted to keep slavery, why would you as a southern soldier risk your life for something you didn’t have? And most people in the south didn’t own slaves. The actual reasons are the high tariffs implemented by the federal government, they were around 15% before 1860 and after they rose to 37%, a growing federal government that wished to take all power away from the states, and if slavery had anything to do with it it was because it was unconstitutional for the government to do anything to prohibit slavery, while I do believe slavery was wrong and should have been abolished much earlier I don’t believe that the government should have the power to take away such a right, believe what you may but these are the true reasons for the War of Northern Agression.