By May 1939, Nazi Germany had already gobbled up Austria and Czechoslovakia. The British Prime Minister Neville Chamberlain and Foreign Secretary Lord Halifax had abandoned the notion that Adolf Hitler could be appeased. Not so Joseph P. Kennedy. The future presidential patriarch and then U.S. ambassador to Great Britain had gone rogue: He ignored the wishes of President Franklin Delano Roosevelt to meet with Helmuth Wohlthat, a top Nazi economic adviser in London, to discuss a way to forestall world war … with a large payoff, in gold.

Despite his efforts and insistence that Hitler could be reasoned with, Kennedy never got close to the führer. As President Donald Trump looks for unorthodox ways to deal with today’s unsavory characters on the world stage — from North Korea’s Kim Jong-un to the Philippines’ Rodrigo Duterte — Kennedy’s fruitless efforts are instructive.

It was insane … Hitler was not going to negotiate with Kennedy. Daivd Nasaw, Kennedy biographer

JFK’s dad made a fortune as a wheeler-dealer businessman, from real estate to the stock market to Hollywood. He threw his money and influence behind Roosevelt’s 1932 presidential bid. FDR then tapped him to run the newly created Securities and Exchange Commission overseeing Wall Street — “Set a thief to catch a thief,” Roosevelt reasoned — but Kennedy would not move up in Roosevelt’s second term to a post like treasury secretary.

“Joe Kennedy had proved something of a misguided missile in Washington,” writes Joseph E. Persico, in Roosevelt’s Secret War: FDR and World War II Espionage. “The right wing saw him as a renegade, a businessman who attacked his own kind.” The left, meanwhile, saw him as someone who could be problematic for labor. He was seen as a “power-hungry publicity hound, a harsh critic of the administration when it suited him, and a man whose business dealings might not stand up to close scrutiny,” Persico writes.

So it wasn’t long before Kennedy was sent abroad, with Roosevelt appointing him U.S. ambassador to Great Britain in 1938. While he proved popular in British high society, he did not get the direct line to the president he craved. On the urgent matter of Germany, the arch-isolationist Kennedy made it his mission to prevent war. And he thought he had the negotiating skills to make it happen.

“The difference between Kennedy and Trump is Kennedy, when he makes a deal — whether a political deal or a business deal — he doesn’t want to get 100 percent,” says David Nasaw, author of The Patriarch: The Remarkable Life and Turbulent Times of Joseph P. Kennedy. “He wants to get more than 51 percent. And he goes into deals thinking that a successful deal is one where the parties on both sides of the table come away happy.” Trump, on the other hand, seems to think a successful deal is “when you make the people on the other side of the table cringe in fear and then leave the table in tears because they’ve lost everything,” Nasaw says.

Through 1938, a sizable group shared the notion that Hitler could be dealt with reasonably. But after Hitler shattered the Munich agreement with the full invasion of Czechoslovakia, the appeasement crowd mostly fell away. But Kennedy held onto hope that the U.S. could settle things not with territory, but with cash, which Hitler sorely needed. So he worked to get meetings with Hitler’s intermediaries in the hopes of eventually reaching the man himself.

James Mooney, General Motors’ overseas director, met in Berlin with a top executive at the Reichsbank and Wohlthat, who was the chief economics adviser for Hermann Göring, a close Hitler confidant. Mooney told Kennedy that Wohlthat, seen as more of a moderate, was open to a “gold loan” and a resumption of trade with the U.S. and Great Britain. Washington rejected the notion, but Kennedy went ahead with a secret May 9, 1939, meeting with Wohlthat in London. Kennedy never got any farther up the Nazi food chain. “It was insane,” says Nasaw. “Hitler was not going to negotiate with Kennedy.”

The freelancing ambassador was wearing thin with his president and his hosts. The Brits started spying on Kennedy, who insisted that aid to the U.K. was merely throwing money at a lost cause. Though he harbored anti-Semitic views, Kennedy was not a Nazi-lover by any stretch. He feared that Hitler and totalitarianism would take over America, and he desperately wanted his son, Joe Jr., to become president. (His firstborn died in the war; John F. Kennedy accomplished the feat instead.)

The final straw for Kennedy’s term as ambassador came in November 1940, when he was quoted in the Boston Sunday Globe saying: “Democracy is finished in England. It may be here [in the U.S.].” Not long after, he resigned his post, and the quote destroyed his own chances for elected office. But it did not hinder the rise of the Kennedys’ next generation.