Original: He conducted the premieres of two Wagner operas , Tristan und Isolde and Die Meistersinger von Nürnberg , in 1865 and 1868 respectively ; both were immensely successful .
Simplified: He conducted the first performances of two Wagner operas : Tristan und Isolde ( 1865 ) and Die Meistersinger von Nürnberg ( 1868 ) .