In September 1966, John Wayne was set to shoot a Western heist movie, but he needed the right co-star to play his character’s former enemy, Lomax.

Burt Lancaster turned down The War Wagon part as he didn’t want to work with Duke, while Rod Taylor was intended for the role until Kirk Douglas, who would have been 108 today, showed interest.

The Spartacus star had already co-starred with the Western legend in Cast a Giant Shadow and In Harm’s Way the previous two years, so he was well acquainted with him anyway.

War Wagon director Burt Kennedy had to give up half his salary to hire Douglas, who was paid $300,000 plus 10 per cent of the gross.

Just before the 12-week shoot began in Durango, Mexico, Wayne was not in good shape, having had his left lung and several ribs removed in a 1964 major cancer surgery.

During the flight over, he had real difficulty breathing on the plane and had to use an oxygen mask the whole way. It was only here that Douglas first realised just how fragile the 59-year-old Duke was, but that didn’t stop the old bull from getting angry with his co-star.

During The War Wagon’s production, Douglas was late to set as he had been shooting a commercial to endorse Edmund G Brown, a Democrat, as Governor of California. This enraged Wayne, a life-long conservative, who was late himself the next day as he’d been filming an advert to endorse the Republican candidate, fellow actor and future US President Ronald Reagan.

Although the two Hollywood stars had their political differences, they eventually became friends and had mutual respect for each other. In a 1971 interview with Dick Cavett, Douglas shut down being asked about Duke’s controversial views on the US taking Native American land.

Cavett brought up that Wayne had said it was “because a lot of people needed land and the Indians were being selfish and thought that they ought to have it.”

Yet Douglas replied: “I don’t want to get involved in a conversation about John Wayne. I’ve made quite a few pictures with John Wayne and, by the way, I’ve always called him John. Everybody calls him Duke. We have never seen eye-to-eye on a lot of things.” However, he did compliment the Western star, saying he was “one of the most professional actors I’ve ever worked with.”

The Spartacus star shared how when working on a movie together, he would only have dinner with Wayne on just one night. He said: “We get along well, we never discuss politics. But he’s the first guy on the set, the hardest worker I’ve ever worked with, and I think he’s quite a character.”

Given Duke’s towering 6 ft 4 height, Cavett joked that it was no wonder the two never saw eye-to-eye. In fact, during his first scene with Wayne, Douglas wore huge lifts so he would look in line with Wayne.