Well done-- up to your usual scholarly standards too.It is actually quite common to have historical accounts from both sides of a conflict. You see, it is very rare for the 'victors' to completely destroy the 'vanquished'. Much more common is that a few battles are fought and each goes and writes the history to serve their purposes.
Now, all history is written with definite *biases*: cultural, political, philosophical, etc. That means a historian must be *very* careful about the interpretation of any writings, even 'first hand accounts'.
An easy example is the one you gave: the 'Civil War' vs the 'War of Northern Aggression'. Both names are clearly biased and convey a particular political view of the conflict. But, both views still agree that there was a war, that certain battles were fought, etc. There are many facts on which even the biased viewpoints are based. Generally speaking, one should be very cautious about claims of who started a conflict: the various sides will often disagree strongly about this. It is common for one side to present a battle as significant while the other side portrays it as a minor skirmish. Guess which side lost?
So yes, history is biased; each side presents its view of what happened and views it through the lens of its own culture, philosophy, politics, etc. But that doesn't mean that it is all fiction. There are still many facts that can be teased out of the biased accounts of the different sides.
I am humbled by your superior patience and willingness to try to educate fools.