There are two distinct forms of historical discourse, those written by participants and onlookers during or in close proximity to events, and those belatedly annotated by scholars, students, authors, that tend to be slanted from a particular perspective. A third variety should exist, being wholly independent narrative without bias or definable purpose beyond the elucidation of fact and the education of the willing to truthful and unembroidered events.
All accounts of past events must be taken as falling into one of the first two camps, either tainted by personal involvement or concurrent prejudices of the period or tipped heavily by the particular socio-political viewpoint of the author, and their position and stature. Works falling under the third imaginary circumstances, independent and nonpartisan renditions, are so scant as to make likely successful interactions mute.
Ergo, all opinions held or formulated about past happenstances must be swallowed with as large a pinch of salt as can be stomached and recognized as highly circumstantial.