Simplify the following text for a Grade 7 native English-speaking person.
Original: After leading a Confederate bushwhacker unit along the Missouri-Kansas border in the early 1860s , which included the infamous raid and sacking of Lawrence , Kansas in 1863 , Quantrill eventually ended up in Kentucky where he was killed in a Union ambush in 1865 , aged 27 .
Simplified: Quantrill lead a Confederate unit along the Missouri-Kansas border in the early 1860s . Quantrill was a leader in the Lawrence Massacre in Lawrence , Kansas in 1863 .