Conversation so far:
What was Abner Doubleday's role in Gettysburg?
At the start of the Battle of Gettysburg, Abner Doubleday's division was the second infantry division on the field to reinforce the cavalry division of Brigadier General Buford.

Question: What side did he fight on?
Self-contained rewrite: What side did Abner Doubleday fight on during the American Civil War?