How does the US Civil War define Americans?

In the Civil War, Americans collectively repudiated slavery, and were willing to fight very hard to preserve their country from being torn apart by secession, so it was a form of redemption and a demonstration of patriotism. America also fought very hard in WWI, and WW II, and the Cold War, and in the current war on terror, so the Civil War would not still be the dominant symbol of American patriotism, but it remains important.