Conversation so far:
what happened to George Armstrong Custer in Hanover?
On June 30, 1863, Custer and the First and Seventh Michigan Cavalry had just passed through Hanover, Pennsylvania
what happened to George Armstrong Custer in Abbotstown?
Next morning, July 1, they passed through Abbottstown, Pennsylvania
where is Hanover located?
Hanover is in Pennsylvania
where is Abbottstown located?
Abbottstown is in Pennsylvania
was there a battle in Hanover?
Hearing gunfire, he turned and started to the sound of the guns. Custer deployed his troops and began to advance.

Question: in what year was he in Hanover?
Self-contained rewrite: in what year was George Armstrong Custer in Hanover?