Conversation so far:
What can you tell me about The Valley?
General George Custer participated in Sheridan's campaign in the Shenandoah Valley. The civilian population was specifically targeted in what is known as the Burning.
What is The Valley and Appomattox?
Shenandoah Valley and Appomattox Court House

Question: What happened in The Valley?
Self-contained rewrite: What happened in the Shenandoah Valley?