I'm no doubt butchering this quote, but In "Who The Devil Made It" Bogdanovich relates that when he told Orson Welles he was going to interview Allan Dwan his response was "My god, Allan Dwan, he was there for the invention of the light bulb!"

Another trivia point, Dwan is generally considered to be the director referenced in the lawn party scene of The Great Gatsby.

Thanks for the comment. David Thomson describes Dwan as "a natural, unpretentious storyteller, capable of real invention on the grand and the intimate scale." He was I feel essentially, a silent director. Of his estimated 1850 films, only seventy or so are from the sound era, and even those could be characterized as silent films with an added soundtrack in as much as Dwan was overwhelmingly visual in style. Although I had never previously considered it, he is actually an extension and development of Griffith in many ways.
Jean-Claude Biette referred to Dwan in Cahiers du cinema as "a great poet of space". While this is an entirely ‘French’ description of a Hollywood original, and one I imagine Dwan himself would find needlessly florid, it is certainly true.
I have not read the Bogdanovich interview, but found several excerpts and references in my research. Needless to say, it is now on my reading list.
Much has been said regarding Dwan’s supposed ‘fall’ from the A list to lesser films in the sound era. What I found seems fairly clear. Dwan loved making films and the process of telling a story through the lens of a camera. What he had not the slightest fondness for was the business and inherent restrictions that came with its development. He admitted on more than one occasion to having made poor contract decisions, but the B movie westerns of his later years also allowed him to work under far less scrutiny than if he’d remained a high profile director in the studio era. I definitely plan a thorough study of Dwan’s films from the fifties at some point (now there’s a NWFF retrospective I’d love to see!).