《资治通鉴·唐纪·唐纪三十三》
史思明得知常山失守，立刻解除对饶阳的包围来救常山。次日天未亮，前锋部队已到达常山，史思明等率大军紧随其后，共二万多名骑兵，直逼城下。
史思明闻常山不守，立解饶阳之围；明日未旦，先锋已至，思明等继之，合二万馀骑，直抵城下。
When Shi Siming learned that Changshan had fallen, he immediately lifted the siege of Raoyang to save Changshan. The next day, before dawn, the vanguard had arrived at Changshan, with Shi Siming and his army following closely behind, with over 20,000 cavalry, pressing the city.