1.  What led up to Gettysburg and the circumstances that resulted in the battle.
2.  Key events and key leaders each day of the battle--what was going on and why it mattered.
3.  The aftermath--what were the consequences of Gettysburg for both the Confederacy and the Union.
4.  Alternative decisions that might have changed the result of the battle.
5.  The military and political significance of Gettysburg to both sides.
6.  An accurate understanding of the geographic and topographic layout of the battlefield and how it influenced the result of the battle.

I have personally visited over 30 Civil War battlefields throughout the United States in both the Eastern and Western theaters.  I was a guest presenter on Gettysburg for a GT course.  I'm writing a historical fiction series where the main character appears at Gettysburg.  I've personally visited the Gettysburg battlefield multiple times with students.