C Span is giving a day by day account by three accomplished historians. Two more days to go.
Basically Lee is invading the North in the hope that Northerners lose their appetite for the war.
The Army of the Potomac has a new leader George Meade.
What is obvious after the first day is the strong defensive position of the Union forces.
The non attempt of Confederate General Ewell to take Cemetery Hill was regarded by historians as a greatly missed
opportunity.
Below is a concise Wiki day by day.
http://en.wikipedia.org/wiki/Battle_of_gettysburg