After graduating from Princeton, Fox worked briefly for the National Broadcasting Company in California before enlisting in the Army and winning the Bronze Star as a signal officer during World War II. After the war, he studied at Union Theological Seminary in New York and earned his doctorate at Defiance College in Ohio in 1952. His career as a minister took him to Arizona, New York, Ohio, Massachusetts and Washington, D.C. He also wrote articles for The Toledo Blade, Christian Century and The New York Times Magazine, where he reported chiefly on community life. His writing caught the eye of President Dwight Eisenhower's staff, and he was hired as speechwriter and liaison to volunteer organizations in Eisenhower's second administration. In 1961, Fox traveled to Northern Rhodesia as a missionary/teacher to instruct African church leaders in the fundamentals of journalism.
Fox planned his own memorial service, even choosing the hymns and scriptures and asking his friends in the Princeton University Band to be present and to play a medley of Princeton songs as a postlude. He was a great supporter of the band, which continues to memorialize him with an annual concert held on the Saturday morning of Reunions weekend.
Fox wrote a "fairy tale" about himself that President William G. Bowen, Graduate School 1958, read at his memorial service:
Once upon a time, there was a little boy who came to Princeton and lived happily ever after.
As an undergraduate, dressed up in a tiger skin, he crashed the gates of Palmer Stadium and cavorted on the field with the Band.
During the war, dressed up like a soldier, he gathered a helmetful of invasion currency from a group of alumni on board a landing ship off the Normandy coast, and sent it back to the University to build a new gym and library.
When peace came, dressed up like a clergyman, he helped edit the hymnbook now used in the Chapel, making sure it contained at least three hymns written by Princetonians.
In the White House, dressed up like a Republican, he drafted messages for D.D. Eisenhower LLD ''7 in the nation's service. Finally, returning home as secretary of the distinguished Class of 1939, he became the only man in history to climb above the belfry of Nassau Hall, and put a 1939 nickel in the gold ball at the top of the pole just below the weather vane.
Fox also created legends of his own:
- With his wife Hannah's help, he sent a homemade Princeton banner to the moon with Pete Conrad '53 as a way, he said, of putting Princeton 239,000 miles ahead of Harvard and Yale.
- While in Red Square in Moscow with other members of his class, he painted two cobblestones orange and black.
- When Japanese visitors came to campus he taught them the words to "Old Nassau," substituting "banzai, banzai, banzai" for "hurrah, hurrah, hurrah."
- When Nassau Hall was being remodeled, he "rescued" a steel crossbeam and dragged it behind his bike to the physics workshop to have it sliced into paperweights.
- He had bricks and mortar and pieces of old fireplaces, and orange and black lollipops, Princeton flags and orange and black balloons which he gave to young and old alike.
- He sent packages of Food Services Tiger sugar to occasionally bitter correspondents to sweeten their dispositions.
- He always insisted that his name was Frederic Fox '39, and that any Princeton name was incomplete without its numerals.
After his death in 1981, his classmates honored his memory by setting up a fund in his name. The Fred Fox Fund provides grants for projects that are conceived by an individual student and relevant to his or her course of study.
Fox's classmate W.C. Bickel '39 gave a portrait (painted by Bickel's wife Minetta) to the University to be hung in the Princetoniana Room of Firestone Library shortly after Fox's death. The painting remained in Firestone even after the Princetoniana Room was relocated in 1990 to Seeley G. Mudd Manuscript Library, where the University archives are stored. Efforts on the part of the Princetoniana Committee, particularly Fox's friends and classmates Hugh "Bud" Wynne '39 and Charlie Dennison '39, to move the portrait to a more public location resulted in its transfer to the 100-level of the Frist Campus Center, complete with a new dedication ceremony, in the fall of 2003.