In terms of its artistic legacy, The Conqueror leaves much to be desired. Routinely making the listing of “The Worst Movies Ever Made,” the 1956 movie starring John Wayne was an unfortunate blemish on the Duke’s acting reputation.

The film depicts the rise of Genghis Khan, giving a fanciful backdrop to the founder of the Mongol Empire. Those who managed to sit through the movie’s full 111 minutes find themselves wondering if John Wayne was truly the best actor to portray the man whose conquering hoards created the largest contiguous empire in history.

There is one startling parallel between the theatrical production and Khan’s life, however. Both left a startlingly-large number of deaths in their wake.

Much of the principal filming was shot near St. George, Utah. It was well situated to provide a somewhat-authentic-looking background to Khan’s Mongolia. It was also well positioned to put the cast and crew in serious danger.

Located 137 miles (220 km) from the Nevada National Security Site, St. George was downwind from one of the most active nuclear test sites on the planet. In 1953 alone, the site was host to Operation Upshot-Knothole, where 11 above-ground nuclear weapons tests were conducted.

The cast and crew of The Conqueror spent weeks at St. George, breathing the irradiated air and treading on fallout-strewn soil. As if that weren’t enough, producer Howard Hughes had 60 tons of the dirt shipped back to Hollywood to use in studio re-shoots.

Two hundred twenty people worked on the cast and crew of the production. Of these, 91 (41.36%) developed cancer. Forty-six (20.91%) died of cancer. Among those who were stricken were stars John Wayne, Agnes Moorehead, Susan Hayward, Pedro Armendariz, John Hoyt, and Lee Van Cleef, as well as director Dick Powell.

Dr. Robert Pendleton, then a professor of biology at the University of Utah, is reported to have stated in 1980, “With these numbers, this case could qualify as an epidemic. The connection between fallout radiation and cancer in individual cases has been practically impossible to prove conclusively, but in a group this size, you’d expect only 30-some cancers to develop. With 91 cancer cases, I think the tie-in to their exposure on the set of The Conqueror would hold up in a court of law.”

As the deaths mounted, Howard Hughes was said to be overcome with guilt. He bought every print of the film for $12 million in an effort to keep it out of circulation. (Possibly, he was also embarrassed about the poor acting.) As he descended into severe mental illness in his final years, The Conqueror was one of the movies he watched on an endless loop.

In the end, you can say that The Conqueror didn’t exactly kill it at the box office. In terms of body count, however, it’s safe to say that it more than made up for that.