How reliable is any history?
It is often said that history is written by the victors ie any account is coloured by the authors point of view.They emphasise what they feel is important and downplay other things or leave them out.
Folk history is often a mixture of true facts that are omitted from the "official" history and "I heard from my mate, who heard from someone who said he was there".
In other words all anybody can do is read the most reliable and unbiased histories and hope to get a reasonable picture of what really happened.