The Civil War was the most devastating conflict in American history due to the immense loss of life and damage to the social fabric caused by Americans fighting Americans. Over 970,000 citizens died, representing 3% of the population, and the war's impact on the economy and development of the country was immense. While ending slavery became the central reason for the war, the original causes were complex and involved states' rights versus federal control. The war left a lasting legacy of preserving the union and ensuring Americans would never again turn their weapons against each other.