Wayne, who was battling health issues and had to use an oxygen mask on the plane to the set, was angry when he found out why Douglas was late to the set one day.

According to reports, Douglas had been shooting a political commercial endorsing a Democrat for Governor of California.

Wayne was known to be a lifelong conservative and had just finished filming an advert for the Republican candidate and future President Ronald Reagan.

The two stars had a history of not seeing eye-to-eye on certain issues.

In fact, Burt Lancaster, who was initially approached for the role that Douglas ended up taking, had turned it down as he didn’t want to work with Wayne.

However, Douglas had already worked with Wayne in two films prior to “The War Wagon,” so the two were already acquainted with each other.

Director Burt Kennedy had to give up half of his salary in order to afford to hire Douglas for the film.

The actor was paid $300,000 plus 10% of the gross for his role as Lomax, Wayne’s character’s former enemy.

The movie was shot over a 12-week period in Durango, Mexico.

Wayne’s health was not in the best condition, having undergone major surgery in 1964 to remove his left lung and several ribs due to cancer.

During the production of “The War Wagon,” Douglas realized just how fragile Wayne was after seeing him use an oxygen mask during their flight to the set.

Despite their political differences, the two eventually became friends and respected each other.

In a 1971 interview, Douglas declined to comment on Wayne’s controversial views on Native American land rights.

Douglas said that he had always referred to Wayne as “John” and never as “Duke” like everyone else did.

Although they had different opinions, Douglas said that Wayne was “one of the most professional actors I’ve ever worked with.”

The two actors did not discuss politics, and Douglas said that they got along well. However, during their first scene together, Douglas wore huge lifts to look taller and be in line with Wayne, who stood at 6ft 4in.

Douglas also revealed that he had only had dinner with Wayne once during the production of “The War Wagon.”

Despite their differences, Wayne was known to be the first person on set and the hardest worker Douglas had ever worked with.

In addition to his role in “The War Wagon,” Wayne was a prolific actor and starred in many films throughout his career.

He was known for his roles in western movies, such as “True Grit” and “The Searchers,” and was a conservative icon in Hollywood.

Douglas, on the other hand, was best known for his role in “Spartacus” and had a long and successful career as an actor and director.

He passed away in 2020 at the age of 103, while Wayne died in 1979 at the age of 72.

Despite their disagreements, the two actors had a mutual respect for each other and their work.

They both left a lasting impact on Hollywood and the film industry as a whole.