Scott at 2012-12-15 21:06:44:

Good question, Phil. Incredible chemistry on-screen. I know Bogart did NOT want to do the movie at first. He was a contract player at Warner Bros. at the time, made his mark doing what WB was most noted for: crime movies. Certainly not like Spencer Tracy and Katherine Hepburn who did, what, 4 movies together?

Joan Adamaitis Agerholm at 2012-12-16 07:16:19:

Or maybe it was just business: two businessmen, Jack Warner and David O. Selznick, had to come to an agreement (as buyer-and-seller) whenever a movie deal was on the table. On the Two-Disc Special Edition DVD of Casablanca, the 2nd disc has a great feature entitled: "You Must Remember This: A Tribute to Casablanca". Among the many contributors there are Julius Epstein, co-screenwriter; Ronald Haver, film historian; and Rudy Behlmer, film historian. They all comment on how difficult it apparently was "to obtain" Ingrid Berman for the movie. At the time, Humphrey Bogart was under contract to Warner Bros., while Bergman was under contract to David O. Selznick. Hal B. Wallis of WB really wanted Bergman for the picture. She was his only real choice for the role of Ilsa. So Wallis sent the two Epstein brothers over to Selznick's office to speak with him. Selznick wanted to hear the story - from the writers - before he agreed to "loan out" his "contracted artist" for Casablanca. They struck a deal: Bergman would be loaned out to WB - for this one film - and actress Olivia de Havilland would be loaned out to Selznick, in exchange. A little weird? Sure. But if this was the studio system at the time, then I can believe how difficult it would be for talent, working under 7-year contracts, to do what they wanted. Plus - after making Casablanca, Bergman's value undoubtable shot straight up. Makes another trade more expensive. That's what I would bet on. John A ps: and I thought that 3-team baseball trades were complicated!