；　the　soldiers　followed　with　a　rush。

Then　Cao　Cao　showed　a　red　flag；　and　the　ambushing　soldiers　led　by　Zhang　Liao　and　Xu　Huang　fell　upon　the　sortie。　The　troops　tried　to　return　and　Cao　Cao's　force　made　a　direct　attack。　The　chase　continued　to　the　drawbridge；　but　there　Cao　Cao's　force　met　with　a　tremendous　shower　of　arrows　and　crossbow　bolts　which　checked　the　advance。　Cao　Cao's　helmet　was　struck　and　the　crest　carried　away。　His　leaders　came　to　pull　him　back；　and　the　army　retired。

As　soon　as　Cao　Cao　had　changed　his　dress　and　mounted　a　fresh　horse；　he　set　out　at　the　head　of　the　army　to　attack　Yuan　Shang's　camp。

Yuan　Shang　led　the　defense。　The　attack　came　simultaneously　from　many　directions。　The　defenders　were　quite　disorganized　and　presently　defeated。　Yuan　Shang　led　his　troops　back　by　the　West　Hills　and　made　a　camp　under　their　shelter。　Thence　he　sent　messengers　to　urge　Ma　Yan　and　Zhang　Zi　to　bring　up　the　supports。　He　did　not　know　that　Cao　Cao　had　sent　Lu　Xiang　and　Lu　Kuang　to　persuade　these　two　into　surrender　and　that　they　had　already　passed　under　Cao　Cao's　banner；　and　he　had　conferred　upon　them　the　title　of　lordship。

Just　before　going　to　attack　the　West　Hills；　Cao　Cao　sent　Lu　Xiang；　Lu　Kuang；　Ma　Yan；　and　Zhang　Zi　to　seize　the　source　of　Yuan　Shang's　supplies。

Yuan　Shang　had　realized　he　could　not　hold　the　hills；　so　he　went　by　night　to　Lankou。　Before　he　could　get　camped；　he　saw　flaring　lights　springing　up　all　around　him　and　soon　an　attack　began。　He　was　taken　aback　and　had　to　oppose　the　enemy　with　his　men　half　armed；　his　steeds　unsaddled。　His　army　suffered；　and　he　had　to　retreat　another　fifteen　miles。　By　that　time　his　force　was　too　enfeebled　to　show　any　resistance；　and　as　no　other　course　was　possible；　he　sent　the　Imperial　Protector　of　Yuzhou；　Y