Rienzi
Rienzi, der Letzte der Tribunen (Rienzi, the Last of the Tribunes) was Richard Wagner's third opera, and the first still in the repertoire, if less common than his later operas. Often described as the "greatest opera Meyerbeer never wrote," Rienzi is not, and should not be, considered one of Wagner's mature works, yet it provides a fascinating insight into how far, and how quickly, he transformed the operatic conventions of his youth.
Origin
The textual origins of Rienzi remain unclear. It's possible Wagner first considered setting Bulwer-Lytton's popular novel Rienzi, the Last of the Roman Tribunes in 1837, shortly after it was translated into German, to divert himself from his marriage to Minna, a marriage about which he had mixed feelings (to say the absolute least) and which would be succeeded by his marriage to Cosima, Liszt's daughter. Alternatively, he may have been inspired by a brief encounter with Mary Mitford's tragedy Rienzi of almost a decade previous. In either case, he assumed work in 1837 and completed it three years later.
Performance and Influence of Meyerbeer
After failing to premiere the opera in Paris, he turned to Meyerbeer, who helped secure a production in Dresden. Among the premiere's stellar cast was Wilhelmine Schröder-Devrient, the original Fidelio. When Wagner originally approached Meyerbeer for his help in seeing Rienzi performed, the older composer asked if he could look at the score, over which he passed a critical, but generous, eye. Wagner would never have admitted to it, but Meyerbeer's enthusiasm for his opera stemmed from the pleasure he gained from seeing his life's work adopted by a rising star of the younger generation. Indeed, Rienzi is impure, adulterated Meyerbeer, a sort of comedy-mirror reflection of Meyerbeer's five-act, Grand operatic spectaculars. The basic ingredients are the same, but - as Wagner admiteed - there are more of them, and their represenation embodies a committed attempt by Wagner to "outdo" the Meyerbeerean school of dramatic clichés and musical inflation.
Structure
The bastardization of the Grand Opera form was never going to produce a work of refinement, but there is nevertheless a profusion of good music. The overture is a well-crafted preview (if at times crude in its militarism) of themes to come over the course of the opera's five hours. Arguably its greatest feature is the cello melody that, after many appearances, is finally developed in the opera's final act, as the celebrated tenor aria "Allmächt'ger vater".
At the end of the day, Rienzi is a historical curiosity, primarily interesting those already greatly familiar with the composer's subsequent achievements who wish for some context to explain the precise origin of Wagner's genius.