Mighty Mouse and the Pirates is a 1945 animated short. It is the 17th short of the Mighty Mouse theatrical series, and the first one to officially feature Oil Can Harry as the recurring cat-villain he becomes later, and to have dialogue sung rather than spoken.
A pirate cat has his eyes set on a beautiful island mouse princess. He and his fellow pirates kidnap the beautiful girl. When singing cat pirates decide to kill all the mice on board for the buried treasure, the natives call to Mighty Mouse for help. Singing his way from the skies, Mighty Mouse flies to the pirate ship, fights buccaneers to the death, and saves the young beauty. He returns her to her people, to their thunderous applause.