While posted in London, he met Rose Lawton Morrison, a college drama teacher from Waycross, Georgia, whom he escorted to Buckingham Palace to meet the Queen. They later married and had eleven children.
Bingham's first assignment in the United States Foreign Service was in Beijing, China. There, he witnessed the beginnings of the communist revolution. His travels through Asia piqued Bingham's interest in eastern religious philosophy. He spent the rest of his life trying to reconcile eastern religious philosophies with that of the Christian traditions his family had been historically known to preach.
Bingham also served in Warsaw, Poland, sharing a apartment with another diplomat, Charles W. Yost, whose daughter, Felicity, became Bingham's god-daughter. In 1934, Bingham served as third secretary to the United States Embassy in London.
On June 10 1940, Adolf Hitler's forces invaded France and the French government fell. The French signed an armistice with Germany. In Article 19 of the document, the French agreed to "surrender on demand all Germans named by the German government in France." Civil and military police began to round up German and Jewish refugees who were marked for death by the Nazis. Several influential Europeans tried to lobby the American government to issue visas so that German and Jewish refugees could freely leave France and escape persecution.
Anxious to limit immigration to the United States and to maintain good relations with the Vichy government, the State Department actively discouraged diplomats from helping refugees. However, Bingham cooperated with Varian Fry in issuing visas and helping refugees escape France. Among those they helped Fry to rescue were famous authors and artists: Leon Feuchtwanger, Franz Werfel, Alma Mahler Werfel, Heinrich Mann, Golo Mann, brother and son of Thomas Mann, Max Ernst, Marc Chagall, André Breton, André Masson, Nobel Laureate Otto Meyerhof, Konrad Heiden, and Hannah Arendt.
He also sheltered Jews in his Marseilles home, and obtained forged identity papers to help Jews in their dangerous journeys across Europe. He worked with the French underground to smuggle Jews out of France into Franco's Spain or across the Mediterranean and even contributed to their expenses out of his own pocket.
Bingham did not speak much about his wartime activities. His own family had little knowledge of them until after Bingham's death; his youngest son discovered a tightly wrapped bundle of letters, documents and photographs in a cupboard behind a chimney in the family home. The bundle told of Bingham's struggle to save German and Jewish refugees from death, details long hidden by the United States government. Bingham's wife Rose and son Thomas also found Marseilles documents in the Connecticut farmhouse which they forwarded to the U.S. Holocaust Memorial Museum in 1991.
On June 27 2002, U.S. Secretary of State Colin Powell presented a posthumous "Courageous Dissent" award to Bingham's children at an American Foreign Service Officers Association awards ceremony in Washington, DC. His son Robert Kim Bingham, Sr. had lobbied the U.S. Postal Service to issue a stamp in honor of his father since 1998. After the proposal received wide bipartisan support in Congress, a commemorative stamp depicting Hiram Bingham IV as a "Distinguished American Diplomat" was issued on May 30 2006.
On October 27 2006, the Anti-Defamation League posthumously presented Bingham its "Courage to Care" award at the ADL’s national conference in Atlanta. In November 2006, the U.S. Episcopal Church added Bingham to a list of "American Saints" published in the book A Year with American Saints with a summary of his life and character.
Hiram "Harry" Bingham IV has received other notable tributes for his rescue efforts during 1940-41, while serving as a U.S. consul in Marseilles.