His writings, which stretched across eight decades, helped Americans understand a president who transformed the office and shaped the postwar years.

NEW YORK — William E. Leuchtenburg, a prize-winning historian widely admired for his authoritative writings on the U.S. presidency and as the reigning scholar on Franklin Roosevelt and the New Deal, has died at 102.

One was a filmmaker, the other a scholarly adviser (who sometimes appeared on camera), and the two became close friends, working together for more than 40 years.