In 598, angry that Ying Province (營州, roughly modern Zhaoyang, Liaoning) had been attacked by Goguryeo, Emperor Wen send his son Yang Liang and the general Wang Shiji (王世積) to attack Goguryeo—a campaign that Gao tried to dissuade Emperor Wen from but Emperor Wen launched anyway, and in fact forced Gao to serve as Yang Liang's deputy.