The melody for "Happy Birthday To You" was first published in 1893 as part of the song "Good Morning to All" written in the United States by sisters Patty and Mildred J. Hill. In 1912, the "Happy Birthday" lyrics were first published, so the song could have been sung as the film is set in 1917 although it did not gain popularity until the 1930s after being spread over American popular culture.