Battle of Boma The Battle of Boma or Battle of Baima was the first of a series of battles that led to the decisive Battle of Guandu between the warlords Yuan Shao and Cao Cao in northern China in the late Eastern Han Dynasty . Although Cao Cao won the battle and Yuan Shao lost an elite general Yan Liang , Cao eventually abandoned his position in Boma to entrench at the strategically important Guandu . Background . By the 190s , the Han Dynasty had fractured into warlordism . After years of reconfigurations and annexations , northern China was divided along the Yellow River by two warlords — the prominent Yuan Shao to the north and his former ally Cao Cao to the south . As it became obvious that a confrontation was inevitable , the two powers scrambled to gather their forces in defensive positions along the Yellow River . At the time , Boma ( 白馬 ; near present - day Hua County , Henan ) laid south of the river across from Liyang ( 黎陽 ; northwest of present - day Xun County , Henan ) , a major base for military recruits . The crossing between Boma and Liyang was deemed to be of tremendous importance as a strategic link in the main north - south route between Yuan Shao and Cao Cao ' s territories . In the eighth lunar month ( September 8 – October 7 , 199 ) , Cao Cao personally advanced to the vicinity of Liyang in a probing action and stationed the Grand Administrator of Dong Commandery ( 東郡太守 ) , Liu Yan ( 劉延 ) at Boma . The position at Boma would allow Cao Cao ' s forces to overlook the vital ford while serving as a first line of defense against Yuan Shao ' s forces . However , Cao Cao had set his sights on a concentrated confrontation at the topographically advantageous city of Guandu ( 官渡 ; northeast of present - day Zhongmu County , Henan ) to the south , thus the purpose of defending Boma might only be to delay enemy advances across the river . Cao Cao also placed Yu Jin at the nearby Yan Ford ( 延津 ; north of present - day Yanjin County , Henan ) with 2 , 000 troops and went back to the capital at Xu City to make further battle preparations . He returned to his battle command at Guandu after putting down Liu Bei ' s rebellion in Xu Province in the first lunar month of 200 ( February 3 – March 2 ) . The battle . In the second lunar month ( March 3 – April 1 ) of 200 , Yuan Shao sent his general Yan Liang with Guo Tu and Chunyu Qiong across the river to attack Liu Yan ' s position at Boma , while Yuan himself stayed behind at Liyang with the main army with the impression that he was crossing the river . Earlier , Yuan Shao ' s advisor Ju Shou had objected to letting Yan Liang lead the attack , saying that Yan is brave but impatient and cannot manage the task alone , but Yuan Shao ignored the advice . Liu Yan ' s small garrison of troops at Boma apparently offered some stubborn resistance , as the siege dragged on for at least 32 days until the fourth lunar month ( May 2 – 30 ) , prompting Cao Cao to lead troops in relief of Boma . If Cao Cao had previously considered the position expendable , then Cao Cao might have been motivated by the time gained by the resistance as well as the need to repair the damages in men , supplies , and morale . As Yuan Shao ' s forces at Liyang was numerically superior to Cao Cao ' s forces , Cao Cao ' s strategist Xun You suggested to split Yuan Shao ' s forces using a diversionary tactic and take out the weakly guarded Yan Liang . Cao Cao adhered to this plan and marched towards Yan Ford as if trying to cross the river to attack Yuan Shao ' s rear . Reacting to this apparent threat , Yuan Shao split off his men in Liyang and came west along the northern bank of the river , thus falling for the feint . Rapidly , Cao Cao led light troops east toward Boma , and engaged a startled Yan Liang some ten " li " west of the outpost . Cao Cao sent Zhang Liao and Guan Yu ( newly surrendered to Cao Cao after Liu Bei was defeated in Xu Province ) to lead the vanguard . Noticing Yan Liang ' s standard from afar , Guan Yu charged through thousands of enemy troops , virtually unopposed , toward Yan Liang , killed him with a stroke , decapitated him , and returned with Yan ' s head . Thus the siege of Boma was broken . Aftermath . After the victory at Boma , Cao Cao considered the outpost at Boma untenable and evacuated its population and equipage to the west toward Yan Ford . With that , Yuan Shao finally crossed the river in pursuit , attacking the baggage train along the southern bank of the river . In what was to become the Battle of Yan Ford , the plundering party was lured into an ambush set up by Cao Cao , killing another of Yuan Shao ' s famed generals , Wen Chou . Thus Cao Cao was able to deal a devastating blow to the enemy ' s morale and retreat back to Guandu unmolested , where Cao Cao had prepared for the eventual showdown . For his efforts , Guan Yu was enfeoffed with the rank of marquis . However , thinking that by killing Yan Liang he had done Cao Cao a great service and repaid Cao Cao ' s generosity , Guan Yu left behind all he had received from Cao Cao with a note of parting and returned to Liu Bei . Cao Cao , in admiration of Guan Yu ' s loyalty , did not allow his generals to give pursuit . In fiction . The Battle of Boma was mentioned in chapter 25 of Luo Guanzhong ' s historical novel " Romance of the Three Kingdoms " as follows : With some 100 , 000 men as the vanguard , Yan Liang attacked Liu Yan at Boma . Answering Liu Yan ' s repeated requests for aid , Cao Cao launched 150 , 000 men split into three prongs to relieve Boma . Guan Yu , who had recently pledged service to Cao Cao and was the subject of many rewards by Cao Cao , wanted to participate in the battle against Yan Liang to repay Cao Cao ' s generosity , but Cao Cao did not think it was necessary to use Guan Yu yet . Cao Cao personally led 50 , 000 men to engage Yan Liang , but was awed by Yan ' s arrays of elite troops . Song Xian and Wei Xu , two former generals under Lü Bu , each volunteered to duel Yan Liang , but were both killed in a short time . Xu Huang also rode out to challenge Yan Liang , but he came back defeated after 20 bouts . Both armies ceased battle for the day . As suggested by his advisor Cheng Yu , Cao Cao then hesitantly summoned Guan Yu , fearing that the latter would leave him once he had repaid his kindness . The next day , as Yan Liang ' s army lined up on the battlefield , Guan Yu sat with Cao Cao on a hilltop and looked down . From afar he saw Yan Liang under the army standard . Leaping onto his steed , the Red Hare , Guan Yu galloped straight into the enemy ranks , which broke before him like waves before a swift vessel . Before Yan Liang could fight back , he was struck down by Guan Yu . Guan severed Yan Liang ' s head , tied it to the neck of his steed , and rode back unhindered . Yan Liang ' s men became demoralized and fell into chaos , providing an opportunity for Cao Cao to attack . The battle of Boma was thus won with uncountable enemy dead and much plundering of supplies .