The most critical issue connected with historical writing in general, and historical novels in particular, is the problem of revisionism. Revisionism is a deadly and contagious condition which afflicts some researchers – and more than a few novelists. Its chief characteristic is the urge to "reveal" something extraordinary to the public, which will cause readers to completely change their opinion about how and why the event being described occurred.
Revisionism is not to be confused with valid new research which fills broadens our knowledge and understanding of historical incidents. This is what legitimate historical research is all about, though the distinction between the two can sometimes by subtle. Revisionism, however, can be clearly identified because its theory is always astoundingly new and sensational and turns an accepted historical happening upside down.
Have you ever noticed that nowadays nothing of consequence happened the way it was originally explained? Napoleon Bonaparte died of cancer, yet now two centuries later, it is widely accepted that he was poisoned by his British guards. Millions of credulous folk firmly believe Princess Diana was not simply killed in an automobile accident caused by her drunk driver, she was "murdered by the British Secret Service". Lone assassin” Lee Harvey Oswald did not kill JFK” -- the dastardly CIA did it. Amelia Earhart did not crash her plane into the Pacific and die; “she came down on a desert island and was shot as a spy by the Japanese.” James Earl Ray did not kill Martin Luther King; he was the patsy for some huge conservative conspiracy. These are just a few typical examples of fashionable (and comical) revisionism.
Although most of these examples are from the 20th Century, wise men throughout the ages have been well aware of this tendency by some to disbelieve the obvious. Why is this belief in "hidden truth" so pervasive? For the public, there are many reasons: an under-lying distrust of anything said by authorities; a need to believe that bad things just could not happen to people in a simple or random manner; and finally, there may be the delight caused by gossip or sensationalism.
For historians, it is even more complicated. As human beings, they are subject to the other motives, but additionally, the very validity of their field of study rests on their ability to revise. There is a fundamental presumption within the discipline that what is known to have happened did not happen in the generally accepted manner or for the generally accepted reasons. Furthermore, their professional reputations and individual egos are based on their revisions. Any historian who investigates the French Revolution and discovers that it simply happened exactly as described in history books is professionally dead. This drive to radically alter the accepted truth is not the only reason many historians change history; they also change it for cultural or national self-interests, or the simple urge for political correctness.