I well remember my disillusionment when I learned that my favorite story of the Norman Invasion of England--that Harold Godwinson died from an arrow in the eye--was untrue. I have since learned that any historian worth his/her salt will tell you that history is a matter of interpretation, not simply memorization of facts. There are far too many factors which color the way that historical events are represented and recorded; therefore any serious student of history must consider bias, point of view, reliability of historical sources, etc. The old expression that history is written by the victors has a great deal of credence. So, other than the few obvious facts, such as the fact that the South lost the Civil War, one should take all historical representations with some degree of skepticism.
Two excellent sources from American history that might help you get a handle on this concept:
Daniel Boorstin's Hidden History
James Loewen's Lies My Teacher Told Me