 Katharine Hepburn joined the cast in mid @-@ April 1942 after Stewart sent her a copy of the unfinished script . Hepburn was fascinated by the character of Christine , and felt that doing the film would be a way of contributing to the war effort . MGM executives did not want Hepburn attached to the picture , feeling it was an inappropriate follow @-@ up for her ( first ) previous pairing with Tracy in Woman of the Year ( 1942 ) , but Hepburn insisted , and MGM relented . Hepburn showed some concerns with Stewart 's redrafting of the script , in that he toned down the novel 's love story , placing more emphasis on the character of O 'Malley role and the action . She asked for more romance in the film . Although Hepburn had spent much of the prior year searching for scripts with equally strong male and female parts for her and Tracy , she now requested that the O 'Malley role be restored to the function it served in the novel ( where O 'Malley is impotent , troubled , and despairing of love ) and her own part expanded . Film producer Victor Saville threatened to resign if the changes were made , and Spencer Tracy supported him , which led to the changes being rejected . 
