I would recommend the Gettysburg trilogy by Newt Gingrich and William Forstchen. It looks at what might have happened if the Confederates had won the battle of Gettysburg.
http://www.amazon.com/Gettysburg-Nov...rds=gettysburg
They also wrote a historical fiction series about Pearl Harbor.
http://www.amazon.com/Pearl-Harbor-D...ref=kinw_dp_ke