The Civil War raged for four years, from 1861 to 1865. From the Dred Scott Decision to the heralded 54th Massachusetts Volunteer Colored Infantry, blacks influenced the war in many ways.
The main reason the South seceded from the Union was that they believed in states' rights over teh federal government. Not until 1863 after President Abraham Lincoln gave the Emancipation Proclamation did the war focus around the subject of slavery. After 1863, the people who died in battle died either for the existence of slavery, the South, or the abolishment of slavery, the North.