What is the dominant theme of the Mexican national anthem?

The lyrics of the Mexican national anthem were written by the poet Francisco González Bocanegra in 1853, and the music was composed by the Spaniard Jaime Nunó; it was first performed on September 15, 1854. Its verses, beginning “Mexicanos, al grito de guerra”, call on Mexicans to defend the homeland against foreign invaders, which is why its dominant theme is defensive war.

A common mix-up is the authors: Bocanegra wrote the words and Nunó the music.