During Cao Cao's campaign against a rival warlord Zhang Xiu, Xu Chu fought on the frontline and slew thousands of enemies. He was promoted to Colonel () for his achievement. In 200, Xu Chu followed Cao Cao to the Battle of Guandu against the northern warlord Yuan Shao. During the battle, Xu Ta () and some conspirators plotted to assassinate Cao Cao. They feared Xu Chu so they waited until he went to rest before they entered Cao Cao's tent with swords hidden under their clothes. Xu Chu felt uneasy earlier on, so he had returned to Cao Cao's tent to protect his lord. When Xu Ta and the others showed up in Cao Cao's tent, they were very surprised to see Xu Chu there and could not contain their astonishment. Xu Chu sensed their intentions and killed them. After this incident, Cao Cao trusted Xu Chu even more and would go nowhere without Xu Chu by his side. Xu Chu participated in the Battle of Ye in 204 and received the title of a Secondary Marquis () as a reward for his efforts. In 211, during the Battle of Tong Pass against a coalition of northwestern warlords led by Ma Chao and Han Sui, Cao Cao led his troops north across the Wei River in an attempt to circle to the rear of the enemy. The bulk of Cao Cao's troops had already crossed the river, leaving Cao Cao and his "Tiger Warriors" to bring up the rear. Just then, Ma Chao and his 10,000 horsemen caught up with them. As the enemies were approaching fast, Cao Cao's soldiers rushed to get on board the ferry, which was on the verge of sinking under the weight. Xu Chu held up a saddle with his left hand to shield Cao Cao from arrows and carried a sword in his right hand, using it to slash enemy soldiers trying to clamber onto the vessel. By then, the boatman had been killed by arrows, so Xu Chu, still holding up the saddle with his left hand, used his other hand to grab a bargepole and push the ferry away from the ford to safety. Cao Cao later agreed to meet Ma Chao and Han Sui for talks, and he brought along only Xu Chu. Ma Chao had confidence in himself and he secretly planned to use the opportunity to charge forward and capture Cao Cao, but he had heard of Xu Chu's might before and he suspected that the man beside Cao Cao was Xu Chu. Ma Chao asked Cao Cao: "Where's your Tiger Marquis?" Cao Cao pointed at Xu Chu, who glared at Ma Chao.