 With the suicide of Emperor Wu's crown prince Liu Ju in 91 BC, his nephew Liu Bo was among the candidates for the title of crown prince.Li was a brother-in-law of Emperor Wu, whose favourite concubine was his sister Lady Li, and was the chosen general in the War of the Heavenly Horses.His supplies for his second sortie are described as being 100,000 cattle, 30,000 horses, and many mules and camels.