Opinion is debatable. Facts are irrefutable
How very true
The trouble is in the academic, historian, world there are endless examples of where "the facts" are seen by many to exist, but then a number of people get together and dispute those "facts", and then can come up with a whole series of counter factual "facts" that justify their argument. Then they claim the"facts" are not "irrefutable".
The list of examples of this is endless but some examples like Wittmann's death are:
The involvement of King Richard III in the murder of the princes in the tower
Queen Elizabeth I involvement or not in the death of the wife of Robert Dudley, Ist Earl of Leicester (boy friend of the Elizabeth)
The sinking of the Titanic......numerous theories and versions of "the facts" about the lead up to, the actual sinking, and the rescue of passengers or lack of it
Churchill and Roosevelt knowledge or not of the Pearl Harbour attack before it happened
Hitler's suicide or not in his Berlin bunker, and his "life" or not beyond 1945..........numerous distortions of known facts, and the promotion of alternative "facts".
President Kennedy's assassination...........numerous versions of "the facts"
The Moon Landings...................
9/11..................
etc, etc, etc.