the Sun Quan's general Zhou Yu culminated in defeat and the destruction of his fleet at the Battle of Red Cliffs. Failing to cross the Changjiang, Cao Cao retreated north. In 211 Cao Cao moved west against Zhang Lu and in doing so also drew the ire of Ma Chao and Han Sui. They were outmaneuvered and defeated at the Battle of Tong Pass. In 212 Cao Cao left Xiahou Yuan behind to continue the northwestern campaign while he returned east to attack Sun Quan across the Huai River. The invasion force reached the banks of the Changjiang but failed to break the enemy defenses. Cao Cao returned to Ye City in 213. In 215 Cao Cao eliminated Zhang Lu and occupied Hanzhong Commandery. Cao Cao attacked Sun Quan again in 217 after Sun Quan's failed attack in 215. However he was never able to make it past the Changjiang defenses but was able to gain Sun Quan's nominal surrender. In the spring of 219, his general Xiahou Yuan was killed at the Battle of Mount Dingjun and Cao Cao lost his position in Hanzhong Commandery. Liu Bei's general Guan Yu also defeated Yu Jin's fores in Nanyang Commandery and laid siege to Cao Ren in Fancheng. However he was unable to take the city and was himself killed when Sun Quan's general Lü Meng who took advantage of the situation and attacked him from behind. Cao Cao died soon afterward on 15 March, 220. He was succeeded by his son Cao Pi. Although primarily known as a military leader, Cao Cao also compiled a commentary on the Art of War and was a renowned poet and player of the game of weiqi. His two most famous poems, Though the Tortoise Lives Long and Short Song Style were written during and right before the battles of White Wolf Mountain and Red Cliff. Later history On 11 December, 220, Cao Pi deposed the last Han emperor and proclaimed himself Emperor of Cao Wei. During his reign Cao Pi alienated his brothers Cao Zhang and Cao Zhi. Cao Pi deeply distrusted his close kin and reduced their powers out of suspicion of their loyalty. Cao Pi died in 226 and was succeeded by his son Cao Rui. Although Cao Rui was twenty years old, he was nonetheless appointed a regency council by his father prior to his death. By 236, three members