The "Guerrillas' Song" is a Chinese patriotic song from the Second Sino-Japanese War (called The War of Resistance Against Japan both in ROC and PRC).
The song describes the guerrilla (i.e. the Chinese resistance) fighters in China during the Second Sino-Japanese War. It was written and composed by He Lüting (贺绿汀) in 1937. The melody has some similarities to "The British Grenadiers" (but it is not known if this song has had any direct influence on its melody).
The song is also sung in Taiwan.