William Clarke Quantrill (1837-1865) was a Confederate guerrilla who is most notorious for leading the August 21, 1863 raid of Lawrence, Kansas, which killed nearly 200 people during the Civil War. His attack outraged the north. In response General Ewing issued his General Order Number 11 which forced the inhabitants of Missouri near the Kansas border to leave unless they could prove their loyalty to the Union.
Quantrill was killed during a raid in Kentucky two years later, on June 6, 1865. [1]