quality:correction
The prewar and war years

As the 1930s came to an end, both Jack and Harry Warner became increasingly alarmed over the rise of Nazism. As Bernard F. Dick observed, the Warners, "as sons of Polish Jews who fled their homeland because of antisemitic pogroms... had a personal interest in exposing Nazism." Moreover, the attraction to films critical of German militarism had a long history with the Warners that predated their production of My Four Years in Germany in 1918. In 1917, while it was still in distribution, the Warners had secured the rights for War Brides, a movie that featured Alla Nazimova as "a woman who kills herself rather than breed children for an unidentified country whose army looks suspiciously Teutonic." Beyond this, Jack was shaken by the 1936 murder of studio salesman Joe Kaufman, who was beaten to death by Nazi stormtroopers in Berlin. He later described the incident in the following terms: "Like many an outnumbered Jew he was trapped in an alley. They hit him with fists and clubs and then kicked the life out of him with their boots and left him dying there." Hence, while other Hollywood studios sidestepped the issue, fearing domestic criticism and the loss of European markets, Warner Bros. produced films that were openly critical of Nazi Germany.

In 1939, the studio released Confessions of a Nazi Spy, starring Edward G. Robinson. The project, which was recommended to Jack by FBI Director J. Edgar Hoover, drew on the real-life experiences of Agent Leon G. Turrou, who had worked as an undercover agent. Despite legal ramifications preventing the use of actual names, the studio aimed for an "aura of authenticity" and Wallis initially recommended eliminating credits to give the film "the appearance of a newsreel." Confessions of a Nazi Spy was widely criticized. The critic Pare Lorentz wrote, "The Warner brothers have declared war on Germany with this one." The German ambassador responded by issuing a protest to Secretary of State Cordell Hull, and the German dictator, Adolf Hitler, who watched the film at Berchtesgaden, was outraged. Meanwhile, the studio received stern warnings from U.S. Congressman Martin Dies Jr. about defaming a "friendly country".

Initially, the studio bowed to pressure from the Roosevelt Administration, the Hays Office, and isolationist lawmakers to desist from similar projects. Jack announced that the studio would release no more "propaganda pictures" and promptly ordered the shelving of several projects with an anti-Nazi theme. In time, however, Warner Bros. produced more films with anti-Nazi messages, including Underground and All Through the Night. In 1940, the studio produced short films that dramatically documented the devastation wrought by the German bombing raids on London. Meanwhile, the studio celebrated the exploits of the Royal Canadian Air Force with films such as Captains of the Clouds. In 1941, Warner also produced the influential war film Sergeant York.

Contemporary reports that Jack had banned the use of the German language throughout the company's studios were denied by studio representatives who indicated that this move would have prevented scores of studio employees from communicating with each other.

After the American declaration of war against the Axis Powers, Jack, like some other studio heads, was commissioned as a lieutenant colonel in the U.S. Army Air Corps.

In 1943 the studio's film Casablanca won the Academy Award for Best Picture. When the award was announced, Wallis got up to accept, only to find Jack had rushed onstage "with a broad, flashing smile and a look of great self-satisfaction" to take the trophy, Wallis later recalled. "I couldn't believe it was happening. Casablanca had been my creation; Jack had absolutely nothing to do with it. As the audience gasped, I tried to get out of the row of seats and into the aisle, but the entire Warner family sat blocking me. I had no alternative but to sit down again, humiliated and furious.... Almost forty years later, I still haven't recovered from the shock."

Also in 1943, Jack, at the advice of President Roosevelt, produced a film adaptation of the controversial book Mission to Moscow, a film intended to inspire public support of the uneasy military alliance between the U.S. and the Soviet Union. Later, while testifying before the House Un-American Activities Committee (HUAC) on October 27, 1947, Jack dismissed allegations during the Cold War that this film was subversive, and he argued that Mission to Moscow was produced "only to help a desperate war effort, and not for posterity." After the film's lackluster response under distribution, the Republican National Committee accused him of producing "New Deal propaganda."

In line with the Warner brothers' early opposition to Nazism, Warner Bros. produced more pictures about the war than any other studio, covering every branch of the armed services. In addition, the studio produced patriotic musicals such as This Is the Army and Yankee Doodle Dandy.