The Royal Court Band of Oz
From the 1908 young adult novel Dorothy and the Wizard in Oz by L. Frank Baum. Based in the royal palace in the Emerald City, they play at occasions of state, such as the grand parade at the end of the novel.
Not to be confused with The Imperial Cornet Band of Oz mentioned a couple pages earlier.
There followed another band after this, which was called the Royal Court Band, because the members all lived in the palace. They wore white uniforms with real diamond buttons and played "What is Oz without Ozma" very sweetly.