On May 21, 1856, Lawrence, Kansas, was captured and sacked by pro-slavery forces.
"The First Sack of Lawrence occurred on May 21, 1856, when proslavery men attacked and looted the antislavery town of Lawrence, Kansas. The assault escalated the violence over slavery in Kansas Territory during a period that became known as “Bleeding Kansas.” The sacking coincided with South Carolina congressman Preston Brooks’s scandalous caning of abolitionist Republican senator Charles Sumner, which had occurred on May 20. The two events were paired and dramatized by the national media, constituting turning point in the lead up to the Civil War."