In 1853, President Antonio López de Santa Anna announced a contest for the lyrics of a new national anthem. The judging committee chose the lyrics of Francicso González Bocanegra, an accomplished poet. After the selection of the lyrics, there was a contest for the melody. A Spaniard, Jaime Nunó Roca, won the contest. The combination of Nunó’s music with González’s lyrics was adopted as national anthem in 1854.
In 1943, when the anthem was officially adopted, the original version of the Himno Nacional was shortened from ten verses to four. When a shorter version is needed such as at sporting events, the chorus, the first stanza and again the chorus are played.[1] When the National Anthem is being performed, one is legally required to remove headgear and stand at attention.[2]
Himno Nacional Mexicano is unofficially known as Mexicanos, al Grito de Guerra.
If you are trying to learn to sing this song I recommend singing along with a YouTube video such as this one: "Himno Nacional Mexicano (El Mas Hermoso Del Mundo)".[3]