This gave Wang Jun (), the commander of the forces in You Province (幽州, modern Beijing, Tianjin, and northern Hebei), with whom Sima Ying had prior disputes, an excuse to attack Sima Ying, and he did so, claiming that Sima Ying was improperly detaining Emperor Hui. Wang's forces were reinforced with ferocious Xianbei and Wuhuan soldiers, and Sima Ying's forces, in fear of their fighting abilities, collapsed, before they could be reinforced with Xiongnu forces under the command of Sima Ying's associate Liu Yuan. Sima Ying was forced to flee to Luoyang with Emperor Hui, now without troops to support him. (Upon hearing Sima Ying's collapse, Liu Yuan, instead of coming to Sima Ying's aid, declared independence from Jin and styled himself the Prince of Han, claiming descent (through a princess) from Han Dynasty, thus creating Han Zhao.)