The Lawrence massacre, also known as Quantrill's raid, was an attack during the American Civil War by the Quantrill's Raiders, a Confederate guerilla group led by William Quantrill, on the Union town of Lawrence, Kansas. The attack on August 21, 1863 targeted Lawrence due to the town's long support of abolition and its reputation as a center for Jayhawkers and Redlegs, which were free-state militia and vigilante groups known for attacking and destroying farms and plantations in Missouri's pro-slavery western counties.