Field Marshal Erwin Rommel was a hero of Hitler’s Germany, the legendary “Desert Fox” who seized the world’s attention with his daring tactics in North Africa from 1941 to 1943.

Manfred Rommel was his only child. He was 15 when he said goodbye to his father, then watched as two German generals ushered him into a car. The generals had given the field marshal a choice: commit suicide or face a rigged trial on charges of conspiring to kill Hitler. If he chose the trial, they said, they could not promise that his family would be safe.

Field Marshal Rommel was guilty of supporting a plot to kill Hitler, who he had decided was leading Germany to disaster. Within minutes, he bit into a cyanide pill and quickly died. It was Oct. 14, 1944.

Manfred went on to become the three-term mayor of Stuttgart, in southwestern Germany. He became a liberal voice in postwar West Germany, supporting the rights of immigrants, backing civil liberties and strengthening the city’s Jewish population....