Exiled from germany and its opera houses, he lived in switzerland for twelve years, where he began work on his massive der ring des nibelungen (the ring of the nibelung). publishers were initially reluctant to support the ring cycle so he interrupted work on it to compose more manageable dramas such as tristan und isolde (1865) and die meistersinger von nürnberg (the mastersingers of nuremberg, 1868).

You're talking about Richard Wagner

Explanation:

Wagner is responsible to introduce the concept of the musical theme (or leitmotif). His compositions tried to capture the essence and the History of German heritage, using nordic mythology as a starting point. The attempt to praise the heritage of his country lead him to compose operas that the strong and union of the German people, however, he constantly advocated avoiding the mixture with foreign populations, praising the German structure, and trying to maintain it pure, as he used to say. These ideas were crystallized by the Nazism years later. It was a genius with complexities.