Waitstill and Martha Sharp were relief workers from the United States who risked their lives to help victims of Nazism. Recruited by the American Unitarian Association, they rescued hundreds of Jews and Christian anti-Nazis from the jaws of death.

Their selflessness, dedication and courage, the stuff of legend, is recounted in Defying the Nazis: The Sharps’ War, a Ken Burns documentary scheduled to be broadcast by the PBS network on Tuesday, September 20 at 9 p.m. (check local listings).

Ardent opponents of the Nazi regime in Germany, the Sharps arrived in Prague, Czechoslovakia, in the winter of 1939, having left their two children in the United States in care of friends. Their mission was to assist Austrians and Czechs who lives had been upended by Germany’s annexation of Austria and the Sudetenland.

Waitstill was a Unitarian minister who had been ordained in 1933, the year Adolf Hitler assumed power in Germany. Martha was a social worker. Both were committed to social justice for all.

Upon arriving in Prague, they set to work to obtain exit visas and jobs in the United States for the people they would assist. Some of them, who were children back then, appear in the film.

Shortly after their arrival, the German army invaded Czechoslovakia, placing the Sharps under still greater scrutiny and pressure. “We realized we were living on the front lines of Nazism,” Martha wrote.

The Sharps were under surveillance by the Gestapo and had to exercise great caution. Apart from having to fend off the Nazis, they had to deal with the problem posed by racially motivated U.S. immigration restrictions.

In one operation, Martha accompanied a group of refugees by train through Germany to Holland and then by boat to Britain.

After leaving Prague, they worked in Portugal and France. In the wake of Japan’s attack on Pearl Harbor, which brought the United States into World War II, they returned to the United States, where they continued to work on behalf of refugees.

As Burns observes, their jobs strained their marriage to such a degree that they eventually separated and divorced.

During the postwar period, Martha was secretly involved in facilitating the immigration of Middle Eastern Jews to Israel. In 2006, she and her former husband were designated as righteous gentiles by Yad Vashem, the Holocaust memorial, education and research center in Jerusalem.

Only five Americans, including the Sharps, share that singular honor.