The Battle of Red Cliffs, otherwise known as the Battle of Chibi, was a decisive battle fought at the end of the Han dynasty, about twelve years prior to the beginning of the Three Kingdoms period in Chinese history. It was fought in the winter of 208/9 AD between the allied forces of the southern warlords Liu Bei and Sun Quan and the numerically superior forces of the northern warlord Cao Cao. Liu Bei and Sun Quan successfully frustrated Cao Cao's effort to conquer the land south of the Yangtze River and reunite the territory of the Eastern Han dynasty. The allied victory at Red Cliffs ensured the survival of Liu Bei and Sun Quan, gave them control of the Yangtze , and provided a line of defence that was the basis for the later creation of the two southern states of Shu Han and Eastern Wu. The battle has been called the largest naval battle in history in terms of numbers involved.