When a mob of armed insurgents flooded the U.S. Capitol on January 6, 2021, they brought an accessory: the Confederate battle flag. As the crowd of President Trump’s supporters rioted, many hoisted the symbol of a short-lived splinter nation that tore the Union apart.

Today, alongside the nation’s growing acknowledgment of systemic racism and widespread Black Lives Matter protests, the Confederate flag predictably makes appearances at white supremacist gatherings.

But how did the battle flag, also known as the Southern Cross, come to represent the Confederacy in the first place? It’s a story of rebellion, racism, and disagreement over the true history of the Civil War—and as the controversy over its use during the Capitol riots shows, it’s divisive