Question: Which opera was written earlier, Rienzi or Amahl and the Night Visitors? 
Sentence (from "Rienzi"): Rienzi, der Letzte der Tribunen ("Rienzi, the Last of the Tribunes"; WWV 49) is an early opera by Richard Wagner in five acts, with the libretto written by the composer after Edward Bulwer-Lytton's novel of the same name (1835).
Relevant evidence: Yes