David Barton is not a historian. And there is no such thing as a “conservative historian”.
Leni
Of course there is. In fact the very father of American conservatism, Russell Kirk was himself a "conservative historian." Some other good conservative historians are Paul Kengor, Bruce Herschensohn, Niall Ferguson, and Victor Davis Hanson. There are many versions of history. There is conservative history and liberal history. Liberal history teaches things like FDR's New Deal saved us from the Great Depression. Conservatives know that many liberal lies are taught as "history."