He could not have been any closer to my idea of Longfellow Deeds, and as soon as he could think in terms of Cooper, Bob Riskin found it easier to develop the Deeds character in terms of dialogue. In Lewis Milestone's adventure film The General Died at Dawn with Madeleine Carroll, he plays an American soldier of fortune in China who helps the peasants defend themselves against the oppression of a cruel warlord. De Mille's sprawling frontier epic The Plainsman—his first of four films with the director—Cooper portrays Wild Bill Hickok in a highly fictionalized version of the opening of the American western frontier.
Cooper later admitted, "It was one of the best roles ever offered in Hollywood ... I didn't see myself as quite that dashing, and later, when I saw Clark Gable play the role to perfection, I knew I was right." In the fall of 1938, Cooper appeared in H. Potter's romantic comedy The Cowboy and the Lady with Merle Oberon, about a sweet-natured rodeo cowboy who falls in love with the wealthy daughter of a presidential hopeful, believing her to be a poor, hard-working lady's maid.
Based on the popular novel by Owen Wister, The Virginian was one of the first sound films to define the Western code of honor and helped establish many of the conventions of the Western movie genre that have lasted to the present day.
Looking to capitalize on Cooper's growing popularity, Paramount cast him in several Westerns and wartime dramas in 1930, including Only the Brave, The Texan, Seven Days' Leave, A Man from Wyoming, and The Spoilers.
Tensions came to a head after von Sternberg yelled directions at Cooper in German.
In Henry Hathaway's The Real Glory (1939), he plays a military doctor who accompanies a small group of American Army officers to the Philippines to help the Christian Filipinos defend themselves against Muslim radicals.
Cooper returned to the Western genre in William Wyler's The Westerner (1940) with Walter Brennan and Doris Davenport, about a drifting cowboy who defends homesteaders against Roy Bean, a corrupt judge known as the "law west of the Pecos".
He was a major movie star from the end of the silent film era through to the end of the golden age of Classical Hollywood.