Mayer tried to express an idealized vision of men, women, and families in the real world they lived in, believing in beauty, glamour, and the star system, with marriage being sacrosanct and mothers being objects of veneration in MGM films. He cherished the Puritan values of family and hard work, making those objectives clear at the outset when he hired writers, once telling screenwriter Frances Marion that he never wanted his own daughters or his wife to be embarrassed when watching an MGM movie. He worshiped good women, honorable men, and saintly mothers, and was serious about that, once coming from behind his desk and knocking director Erich von Stroheim to the floor when he said that all women were whores. Mayer knew that formula in his themes and stories usually works, feeling that the general public, especially Americans, like to see stars, spectacle, and optimism on screen, and if possible, with a little sentiment attached. They don't like to be challenged or instructed, but comforted and entertained, so having messages was less important to Mayer than giving his audience pure entertainment and escapism. In his screen dramas, he wanted them to be melodramatic, whereas in comedies, he often laced them with strong doses of sentimentality, and he loved swaggering, charismatic hams like Lionel Barrymore and Marie Dressler. Musicals were high on his list of preferred genres, and on a hunch, he asked songwriter Arthur Freed to be associate producer for The Wizard of Oz, and Freed's unit at MGM produced many films considered among the best musicals ever made, including For Me and My Gal, Girl Crazy, Meet Me in St. Louis, The Harvey Girls, The Pirate, Easter Parade, The Barkleys of Broadway, On the Town, An American in Paris, Singin' in the Rain, The Band Wagon, and Gigi. Mayer's greatest contributions to posterity are said to be his musicals, with both An American in Paris and Gigi winning the Academy Award for Best Picture. During World War II, Mayer understood that the Germans could ban or boycott Hollywood films throughout much of Europe, with 30 to 40 percent of Hollywood's income coming from European audiences, but he still authorized the production of anti-Nazi films like The Mortal Storm and Escape, and defied pleas to stop making pro-British and anti-German films by producing Mrs. Miniver, a simple story about a family in rural England trying to get by during the early years of the war. The film won six Academy Awards and became the top box office hit of 1942, with President Franklin D. Roosevelt and British Prime Minister Winston Churchill both loving the film, and Churchill sending Mayer a telegram claiming that Mrs. Miniver was propaganda worth 100 battleships.