Final answer:
The epic poem about the fictional Argentine named Marti Fierro is called El Gaucho Martín Fierro. It tells the story of a gaucho warrior and his struggles with the social and political changes happening in Argentina.
Step-by-step explanation:
The epic poem about the fictional Argentine named Marti Fierro is called El Gaucho Martín Fierro. It was written by Argentine writer José Hernández and was first published in 1872. The poem tells the story of a gaucho, or Argentine cowboy, and describes his life as a warrior and his struggles with the social and political changes happening in Argentina at the time.