Before final casts were announced, Robert Stack, Dick Foran, Diana Barrymore, Evelyn Ankers, Jon Hall, Nigel Bruce and Patric Knowles were considered by Howard Hawks. In the June 11, 1942 issue of The Hollywood Reporter, Robert Rosson was to be the second unit director on the film, shooting 10 days on location in the Atlantic with a convoy, and Hawks was going to direct, as well as produce. Screenwriter Lt. John Rhodes Sturdy, the commanding officer of a Canadian corvette, was also assigned to the film for five weeks as a technical advisor, loaned to the production by Royal Canadian Navy Public Affairs.
