John Wayne's incredible kindness to Humphrey Bogart and Lauren Bacall

Back in 1955, John Wayne starred in the Cold War adventure film Blood Alley, about a voyage from the Communist Chinese coast to Hong Kong.

Hollywood gossip columnist Hedda Hopper, Duke's fellow conservative, tried to persuade him not to work with Lauren Bacall over her liberal politics, but he went ahead anyway.

Meanwhile, the leading lady herself had initially signed on to star opposite Robert Mitchum as Captain Wilder.

Yet, when he left the project, Wayne signed on for the role he would later admit he was miscast in.

Bacall expected to clash with Duke over their polarised political opinions, but, as was often the case with the likes of Kirk Douglas, he avoided the topic and ended up being a charming friend.

Bacall later said: "That was supposed to be [Robert Mitchum], but he got into some brouhaha--probably had a few too many. [Director William A. Wellman was great; Wild Bill, a fascinating man! Not a good movie, but I liked working with Duke. We didn't agree politically, but we got along well and had a sort of chemistry." When her husband, Humphrey Bogart, visited the Blood Alley set, she was even more surprised by Wayne's character.

A couple of years later, Bogart was dying from cancer, and Wayne was the first to send the Casablanca star flowers. Bacall noted this was especially kind of Duke, as he barely knew his fellow Hollywood star. The two co-stars remained friends for the next 24 years, working together again on Duke's final film, The Shootist, which was almost cancelled because he was so ill.