Bette Davis repeatedly clashed with director Herman Shumlin throughout production. A novice film director, he had no real experience on a film set and certainly none in dealing with a prima donna actress like Davis. Producer Hal B. Wallis was forced to lean hard on Shumlin when he saw how over the top Davis was in her performance.
This adaptation of Lillian Hellman's play was written by her longtime companion, Dashiell Hammett. Hellman was unable to write the adaptation herself as she was contracted to work on the screenplay for The North Star (1943). She recommended that Hammett be given the assignment as he was very familiar with the material. (Hammett also needed the money.)
Bette Davis gladly took on a supporting role as she wanted audiences to see what she considered to be a very important film and also because she admired Lillian Hellman's writing having recently worked on the film version of Hellman's The Little Foxes (1941).
Jack L. Warner paid $150,000 for the rights to the play which had enjoyed a successful run on Broadway. Warner had great faith in the material, feeling that its patriotic nature would go down well with wartime audiences.
Producer Hal B. Wallis originally wanted Charles Boyer for the male lead before deciding that Boyer's French accent would prove counter-productive. Instead, he went with Paul Lukas who had originated the role on Broadway.
Pre-production on the film had to be halted whilst writer Dashiell Hammett recovered from a bad back. By the time he was able to resume work some months later, the production of Now, Voyager (1942) had concluded and Bette Davis was now available.
Bette Davis fought hard with the studio about putting her name as top billing, as she knew her part was essentially a supporting role. However, this was a fight that she lost as the studio rightly figured that people would queue up to see a Bette Davis movie as opposed to a Paul Lukas one.