in effect, he was not truthful, and Emperor Wen began to distance himself from Gao. Further, in 598, when Gao, under Emperor Wen's duress, was forced to accompany Yang Liang, the Prince of Han, in a campaign against Goguryeo, a campaign that he opposed, the campaign ended in failure, and Empress Dugu blamed him for the failure, particularly after Yang Liang, angry that Gao was not following his orders, complained to her. Another person who began to draw Empress Dugu's ire was her son, Yang Yong, the Crown Prince. When he was young, Emperor Wen and Empress Dugu had selected for him a wife from the honored Yuan clan, Northern Wei's imperial clan—the daughter of the official Yuan Xiaoju (元孝鉅). However, Yang Yong did not favor Crown Princess Yuan, and instead had many concubines, including his favorite Consort Yun, and he did not have any sons with Crown Princess Yuan. When the Crown Princess died in 591 after a brief illness, Empress Dugu suspected Yang Yong and/or Consort Yun of poisoning her, and rebuked Yang Yong. The second son of Emperor Wen and Empress Dugu, Yang Guang, the Prince of Jin, who had ambitions of displacing his older brother, put on pretenses of living frugally (which pleased Emperor Wen) and loving no one but his wife Princess Xiao (which pleased Empress Dugu). By 599, both Emperor Wen and Empress Dugu were considering replacing Yang Yong with Yang Guang, but when Empress Dugu once approached Gao with the issue, he stated firmly that the Crown Prince should not be replaced. Therefore, Empress Dugu suggested that Emperor Wen remove Gao and he was accused of crimes, removed from his office and reduced to commoner rank. Meanwhile, Yang Guang was continuing to provoke Empress Dugu, falsely stating that he feared that Yang Yong would eventually put him to death. Yang Guang further entered into an alliance with Yang Su, with whom Yang Yong had a poor relationship, and Empress Dugu also told Yang Su to encourage Emperor Wen to depose Yang Yong. Subsequently, Yang Guang engaged Yang Yong's associate, Ji Wei (姬威), to falsely accuse Yang Yong of plotting treason. In 600, after an investigation conducted by Yang Su, in which he manufactured evidence against Yang Yong, Emperor Wen deposed the Crown Prince and put him under house arrest, replacing him with Yang Guang. In fall 602, Empress Dugu died, and Emperor Wen