Lohengrin Prelude to Act III. Lohengrin, WWV 75, is a Romantic opera in three acts composed and written by Richard Wagner. This brilliantly jubilant Prelude to Act III (Vorspiel 3. Aufzug in german) is an example of Wagners deft hand with a brass melody blazing through a whirl of strings. It is is frequently performed separately as a concert piece.