How did this action change things for the better? How would history have turned out differently had the empire remained united?
The part of your post body about "how would history have turned out differently" is not within the scope of this subreddit as noted in the rules section on "Is this the right place for your question?":
Questions should be about what did happen, not what could have happened. Questions of that type should be posted in r/HistoryWhatIf.