‘How to Win An Information War: The Propagandist Who Outwitted Hitler’
By Peter Pomerantsev
Public Affairs, 304 pages

‘Cracking the Nazi Code: The Untold Story of Agent A 12 and the Solving of the Holocaust Code’
By Jason Bell
Pegasus Books, 352 pages

The propagandist is Sefton Delmer, about whom I first heard from one of his journalist friends, Rivers Scott, after he became my British literary agent. Rivers spoke of Delmer with awe — and no wonder, as Delmer covered nearly all the major foreign news for the Daily Express. Yet he had quite another job during World War II: figuring out how to neutralize Hitler’s commanding radio voice.

All sorts of people in Europe and America — whatever their political persuasion — hung on Hitler’s words, as I realized when I read the diary of actor Dana Andrews, who described his fascination with the performance of a role that epitomized the Nazi domination of the public imagination. It did little good, Delmer realized, to simply call Hitler evil, or to try to correct his disinformation. Something more dramatic was needed, so he created his own Hitler nemesis: der Chef.

“There was something almost daggerlike in der Chef’s tone,” Peter Pomerantsev observes: “sharp, maybe drunk, definitely bitter. He swore incessantly, with racial slurs about Yankee-swine, stink-Japs, Russian pig-Bolsheviks, and Italian lemon-faces.” He called Churchill a “dirty, Jew-loving drunk.” Der Chef loved the army but loathed the Nazi party.

It was all an act on the radio every day for 10 minutes, delivered by a German actor Delmer had hired. This story that Delmer was never able to tell is now revealed, as well as the reasons why we had not known it: “the victorious Allies didn’t want anyone to think ‘the war had been won with a trick.’ This was, after all, meant to be ‘our finest hour,’ when our most virtuous qualities shone through, not when we excelled at the darker arts.”

Delmer, stationed in Germany in the 1930s, went out drinking with Nazis in order to understand the power of their propaganda, and to use their own tools against them. All this is not academic to Mr. Pomerantsev, who is a disinformation expert in the thick of trying to combat President Putin’s lies about the invasion of Ukraine, an eerie simulacrum of Hitler’s belief that he was uniting one people across the borders of Austria, Czechoslovakia, and beyond. Like Delmer’s subversion of the Nazi propaganda machine, Mr. Pomerantsev is looking for ways to disable the Russian dictator’s “media system.”

Jason Bell calls Winthrop Bell “quite possibly history’s greatest spy,” the “first Western secret agent to fight the Nazis” — as early as 1919. Like Delmer’s story, Bell’s has not been told, because spies don’t tell. “Naturally, I have not talked of it,” he confided to a fellow spymaster. Like Delmer, Bell lived inside Germany for crucial periods. A university-trained epistemologist, he treated the gathering of intelligence as a mission to document “Hitler’s plans for worldwide genocide.”

Bell (no relation to the author) was there during Nazi marches carrying with him a copy of Hitler’s “Mein Kampf,” matching what he said to the shouts in the Berlin streets repeating the book’s horrendous summons to “hatred, revenge, uncompromising enmity,” with the marchers proclaiming that “these must be our watchwords.”

Winthrop Bell, a historian and philosopher as well, did not need Hitler to spell it out. Instead, Bell noticed how the führer “cleverly pointed his followers to ancient historical examples in which conquerors had slaughtered defeated populations.” Bell read and understood in the original German that all non-Aryans were expendable.

By 1939, at least two years before the first reports of widespread exterminations, Bell realized that Hitler had decided that the only way to protect German blood from contamination — racial poisoning — was to murder entire non-aryan populations. Bell put his own life at risk in his role as a secret agent, and like Delmer he approached his work with a cunning sense of humor that served as his disguise.

Everyone thought Bell was “nice.” He looked younger than his age, which for a spy and scholar made him seem less formidable. As one friend said of him: He was “winning and unaffected,” wearing his learning lightly — the very thing to be desired in a successful spy.

Mr. Rollyson’s work in progress in “Making the American Presidency: How Biographers Shape History.”