The National Anthem of Spain is the “Grenadier March”. Next to the flag and the Shield It is a National Symbol.
It has no lyrics and its author is unknown. It is called “Spanish Royal March” why Carlos III The March of Honor declared it in 1770 and was interpreted in the acts attended by the members of the Real home. Only during the II Republic (1931-1939) was replaced by the Hymn of Irrigation.
It was elevated to the category of National Anthem by the custom of using it, although there was no written order for it to be.
There were several attempts to write lyrics but they were sterile: no lyrics were of sufficient quality. As a curiosity I can tell you that until 1997 the State did not acquire the rights to exploit the work.