David Roll, a Washington-based attorney, has written books on Harry Hopkins, George Marshall, and Louis Johnson. Now comes his fourth book, "Ascent to Power," which focuses on Franklin Roosevelt's final days through the sudden transition to the presidency of Harry Truman. Spanning the years 1944-1948, David Roll's newest book looks at the struggles of a relatively unknown Missouri senator, Harry Truman, who had served the U.S. as vice president for only 82 days before FDR's death on April 12, 1945. This is the first of a 2-part interview with David Roll. Part two will be posted next week.

Learn more about your ad choices. Visit megaphone.fm/adchoices