War Between the States, 1861-1865, simulates the American Civil War from the opening shots at Fort Sumter to Lee's surrender at Appomatox. During that conflict, over 3 million men fought from a total pre-war population of some 30 million. About half-a-million died or were permanently incapacitated by disease or combat wounds. It was the great crisis of American history to date.

The American Civil War was the first modern war. It was overwhelmingly a war of attrition between nation states. Given the enormous personnel and economic superiority of the Union over the Confederacy — a consideration reflected in the game — the South usually loses. It is therefore normally a question of how quickly the South loses, compared with the historic outcome, which determines who wins each game.