Empress Cao (曹皇后, personal name unknown) was the wife of Dou Jiande, an agrarian rebel leader who claimed the title of Prince of Xia at the end of the Chinese Sui dynasty.
She was said to be frugal in her living, as even after Dou conquered modern Hebei and had substantial holdings, she had no decoration on her clothing, and only had less than 10 maids attending her.
(Novels fictionalizing the era generally attribute Dou's disbanding of the ladies in waiting to his love for her and her jealousy, but nothing is recorded in history suggesting that she was, in fact, jealous.)
As he approached Luoyang, his strategist Ling Jing (凌敬) suggested that instead of heading to Zheng's capital Luoyang, which Li was sieging, that he attack Tang's Fen (汾州, roughly modern Lüliang, Shanxi) and Jin (晉州, roughly modern Linfen, Shanxi) prefectures and be poised to further attack Tang's capital Chang'an in order to seize Tang territory as well as force Li to give up the siege on Luoyang.
[1] The official Qi Shanxing (齊善行), however, persuaded the others that further resistance would be futile, and the treasures that the Xia state had previously obtained were distributed to the soldiers, who were then disbanded.