This article analyzes the concept of «nationalism» as it appears in Numancia, by Miguel de Cervantes y Saavedra. We show that, although the term did not exist at that time, the author is translating into his tragedy the physical and metaphysical references of the Spanish nation cult, from Renaissance codes. From a systematic lexical and formal study, although the content will reach the conclusion that Numancia can be considered as a dialectical approach in four acts, which concludes with an aesthetic and ethical definition of what we have been calling «nationalism», even if Cervantes gives us an original representation of the Spanish nation.