Claremont McKenna Professor Harry V. Jaffa exerted a considerable influence on William F. Buckley Jr., says Richard Brookhiser in The Wall Street Journal. Brookhiser worked for Buckley at The National Review. He discusses his early involvement with Buckley in this video, accessible here. Here is what he has to say about the influence Jaffa's "historiography" had on Buckley.
Early in [Buckley's] career he justified obstacles to black suffrage in the South -- "the white community," he wrote in 1959, "is entitled . . . to prevail politically because, for the time being anyway, the leaders of American civilization are white." He ended his career in despair over the Iraq War, concluding as early as 2005 that we should bug out -- "our part of the job is done as well as it can be done, given limitations on our will and our strength."He changed his mind on both issues, embracing the civil-rights historiography of the political scientist Harry V. Jaffa and supporting the surge in Iraq when it began in 2007. Being wrong is the risk you run by thinking and acting. The only people who are never wrong are hermits -- unless withdrawing from the arena is itself wrong. For Buckley quietism was never an option.