gǔ / dài / jūn / duì / chū / zhēng / shí / yíng / mén / qián / cháng / cháng / shù / zhe / yí / miàn / zào / dào

古代军队出征时，营门前常常竖着一面皂纛。

When ancient armies went to war, a black banner was often erected in front of the camp gate.