The following press release was published in May, 1964
"Frank Sinatra will star in Von Ryan's Express at 20th Century Fox. Based on David Westheimer's bestseller about mass escapes from Italian prison camps during WWII, the drama will be produced by Saul David with Mark Robson directing. It is scheduled to start in mid-summer with possible location in Italy."
(Note: the press release was inaccurate in the sense that the film did not deal with massive "escapes" from multiple prison camps. Rather, it dealt with only one escape from one camp. However we suppose it's a bit too late to demand that the press writer be fired.)