The Standard Parade (1939)

A live action black-and-white prolog tells the story of how Walt Disney came to Hollywood with $300, was rejected by all the major studios, but went on to tremendous success, many awards, and a thriving studio. Titles then ask what this means to the Standard Oil Salesman, and a parade of Disney characters gives us the answer, featuring Mickey as drum major, Minnie carrying a banner, and the 7 Dwarfs carrying the letters "STANDARD" (Dopey gets stuck with the last two): Apparently the various ads for Standard will be featuring Disney characters in the coming year.