Yes - ultimately it was. Look, ever since the Founding Fathers declared independence in 1776, slavery was an issue. Matter of fact when writing the Constitution, the matter of slavery was a compromise - putting the country together took precedence. Every major issue that presented itself from 1776 to 1860 was for the most part ironed out - except slavery.
Sure in 1860, there were other issues between the North and the South but slavery was the 1,000 pound elephant in the room. The Civil War was American Destiny - it was inevitable from the day America decided to become it's own country.