"the resounding strains of the Polonaise"

The Polonaise is a slow dance originating from Poland: hence the name. It has three beats in the bar, like a waltz. Chopin wrote a great many famous Polonaises, such as the Polonaise Fantasie No. 7 in A Flat (Listen to it on Spotify.) It was also widely used by Russian composers. The dance is commonly used at celebratory events; for example, in Poland, the Polonaise is always the first dance at the graduation ball which celebrates the end of high school.