Wait! I thought he was right-handed.
April 4, 1953 - Trouble Along the Way released (USA).
Trouble Along the Way is a 1953 comedy film directed by Michael Curtiz and starring John Wayne, Donna Reed, and James Coburn. During one of the tackle stunts, Wayne injured his right arm and wore his arm in a sling when he wasn't in shots for filming. He learned how to throw and write left-handed during filming so his character in the film is left-handed when the Duke is really right-handed.
A Variety review noted that "Donna Reed gives her role as a probation officer all that it needs to hold its own with the two male stars, besides being a looker."