He went on to become an outspoken defender of Republican and Abolitionist causes in Brazil, and was active in campaigns that ultimately led to the overthrow of the Monarchy and the establishment of the First Brazilian Republic in 1889.

His struggle on behalf of nationalism in classical music led him to work at the Popular Concert Association from 1896 to 1906, where he pushed for the recognition of several Brazilian composers.

As Grieg was also an advocate for nationalism in composition, the friendship was instrumental in convincing Nepomuceno to write music that reflected Brazilian culture.

In addition, Nepomuceno was a significant influence on many early 20th-century Brazilian nationalist composers such as Heitor Villa-Lobos, which became one of his students, Luciano Gallet, and Oscar Lorenzo Fernández.

Back in Brazil, he championed the use of Portuguese in opera and song and remained the leading musical figure in the country until his death at age 56.

Also notable are the operas Abul (1905), Artemis (1898), Electra (1894) and O Garatuja (unfinished), the Orchestral Pieces (1888), the Sinfonia in G minor (1893) and the Serenata (1902).

"O Guaratuja" is the nickname of the protagonist of the story, who is an artist with a penchant for scribbling graffiti on the walls of urban buildings.