田汉 wrote the words and
聂耳 the music in 1935, as the theme song of the film
风云儿女 about resisting the Japanese invasion; the 'volunteers' were the irregular armies that fought the Japanese in the northeast after 1931. It became the provisional anthem in 1949. During the
文化大革命 Tian Han was denounced and the words could not be sung; new words were used from 1978, the original ones were restored in 1982, and the anthem was written into the constitution in 2004.
