The "Guerillas' Song" (simplified Chinese: 游击队歌; traditional Chinese: 游擊隊歌; pinyin: yóu jī duì gē) is a patriotic song from the Second Sino-Japanese War (called The War of Resistance Against Japan (Chinese: 抗日戰爭) both in ROC and PRC).
The song describes the guerrilla fighters of the Chinese Communist Party. It was written and composed by He Lüting (贺绿汀) in 1937.
The song is also sung in Taiwan.
References
Guerrillas' Song Wikipedia(Text) CC BY-SA