Recently The Civil War Monitor asked several historians (including yours truly) their opinions about Thomas J. “Stonewall” Jackson. The answers appear in the current issue, but space restraints in the paper edition offered an opportunity for the journal to share on its website how people responded to that traditional counterfactual query, “What if Stonewall Jackson had been at Gettysburg?”
You can find the answers here.
It’s a question that is as problematic as it is popular. I’ve tired of it, largely because I’ve learned that people who don’t know nearly as much about the Civil War as they claim to know prefer to talk about what could have happened (where research and knowledge gives way to fantasy and imagination) than to discuss what really did happen and why (thus Civil War discussion groups thrive on such debates). Besides, there are other what-ifs I find more interesting.
Nevertheless, these discussions are just the thing for people who like that sort of thing, so enjoy.