The South lost
As an aid to remembering who lost the American Civil War, associate South with Slavery using the S at the start of each word. We know that slavery is evil, so they had to lose!

SOUTH = SLAVERY = EVIL = MUST LOSE
As an aid to remembering who lost the American Civil War, associate South with Slavery using the S at the start of each word. We know that slavery is evil, so they had to lose!

SOUTH = SLAVERY = EVIL = MUST LOSE