Complex sentence: The Prince of Denmark's March, commonly but erroneously called the "Trumpet Voluntary", is a musical composition written about 1699 by Jeremiah Clarke, the first organist of the then newly rebuilt St Paul's Cathedral.
Split into simpler sentences: The Prince of Denmark's March, commonly, though erroneously, known as the "Trumpet Voluntary", is a work by Jeremiah Clarke, composed around 1699. Clarke was the first organist of the then newly rebuilt St Paul's Cathedral.