I don't know anything about Fisk. I looked up his wiki bio after his name was posted, it looks like he has some serious credentials, I was wondering why you hold this opinion?
From a review in the Guardian of his book The Great War for Civilization:
"The book contains a deplorable number of mistakes. Some are amusing: my favourite is when King Hussein's stallion unexpectedly "reared up on her hind legs". Christ was born in Bethlehem, not Jerusalem. Napoleon's army did not burn Moscow, the Russians did. French: meurt means dies, not blooms. Russian: goodbye is do svidanya, not dos vidanya. Farsi: laleh means tulip, not rose. Arabic: catastrophe is nakba not nakhba (which means elite), and many more.
Other mistakes undermine the reader's confidence. Muhammad's nephew Ali was murdered in the 7th century, not the 8th century. Baghdad was never an Ummayad city. The Hashemites are not a Gulf tribe but a Hijaz tribe, as far as you can get from the Gulf and still be in Arabia. The US forward base for the Kuwait war, Dhahran, is not "scarcely 400 miles" from Medina and the Muslim holy places, it is about 700 miles. Britain during the Palestine mandate did not support a Jewish state. The 1939 white paper on Palestine did not "abandon Balfour's promise" (and he was not "Lord Balfour" when he made it). The Iraq revolution of 1958 was not Baathist. Britain did not pour military hardware into Saddam's Iraq for 15 years, or call for an uprising against Saddam in 1991. These last two "mistakes" occasion lengthy Philippics against British policy; others may deserve them, we do not."
He changes facts to suit the narrative he is trying to advance, which makes him little more than a propagandist in my view. I have no tolerance for "journalists" masquerading as historians. His books are not up to par with those of actual historians.