The Three Musketeers was there any facts to this or all just a fable?

With Sir Walter Scott, Dumas was a master of the historical Novel. Dumas used a lot of history, and real people. There was a rumor of a man in the iron mask. But it was not the King's brother. There was never a Count of Monti Cristo. Louis the 13th, 14th (sun king), Richelieu, Duke of Richmond were real, but never interacted like in the D'Artagnan Romances. By the way we are talking about five or six books here.