Tell me about the American Civil War
The American Civil War was fought from 1861 - 1865 between the Union (North) and Confederate (South) armies.  The Union was thought to have an easy path to victory since it enjoyed the advantages of a more modern industrial economy and greater numbers of fighting aged-men.  However, the war dragged on for much longer, and at a higher cost than most initially imagined - carrying on 4 years and at a cost of about 600,000 dead.  The Union won, and the United States was saved from a constitutional crisis as a result.