The era of Three Kingdoms, and the decades leading up to the time, was full of strife, assassinations, betrayal, and brutal battles - never before seen during the 400 year history of Han China. Tens of thousands of men in mail coats and a thousand more heavy cataphracts fought each other. And in the midst of the fighting emerged key figures. Some were heroes by the likes of Lui Bei, others were tyrants such as Dong Zhuo. All these infighting caused the once-glorious and grandiose Han Empire to crumble, infected by a plague from within.

From the ashes of the fallen empire was plenty of warlords; seeking to fill the power vacuum left by the weak Imperial government and the unforeseen assasination of Dong Zhuo. As history remembers, civil war never ends well. Hundreds of warlords, each with their respective territories and armies of men battled over vital supply routes, key cities, or conquering as a whole.

See from the map above, the territories of various warlords and governors vary. Most warlords have their territories well protected. For instance, Ma Teng, warlord of Xi Liang, though maintaining a relatively small force of 10,000 men strong, is protected by the vast expanse of Western China - the harsh climate, desert gales, and mountains. Other warlords such as Liu Biao, Sun Ce, and Yuan Shu have the Yangtze River (running across their lands) for defense. The northern warlords like Yuan Shao and Gongsun Zan have the cold northern weather for defense; much like the Russians. Some have protection from the lack of frontiers with enemies, thus being able to concentrate their forces.

Only the great tactician Cao Cao was in an awkward position - both practically and metaphorically. Practically, his land was smack in the center of other warlords which was very dangerous. Increasingly so, in fact. Cao Cao was a bulwark for enemies. Warlords could just ally against him and Cao Cao’s great legacy would be cut short of glory. Alone, Cao Cao could not defeat anyone, even with his strategic skills. He was hopelessly outnumbered if war came.

To prevent any attacks from neighboring warlords, Cao Cao needed allies to come to his aid in times of need. Cao Cao had found some possible candidates but Yuan Shao, to his north, is the most beneficial ally. Firstly, Yuan controlled the province of Hebei, which is a powerhouse for supplies and war material. Hebei, in modern geography, is located in a temperate zone - climate zones that have the widest seasonal changes - warm springs and summers and cold winters. Thus, crops are able to grow unhindered and in full supply. Cao Cao, who lacked sustainable provision output, needed to use Yuan Shao’s supplies to secure a strong position. Second, Yuan Shao leads a powerful army. If Cao Cao was to be allies with Yuan Shao, Yuan would be obliged to come to Cao Cao’s aid in a time of need.

Yuan Shao also needed Cao Cao to unite the north. Yuan Shao desired to have sole hegemony over the north. Cao Cao should fend the other warlords at bay while Yuan is campaigning. Once Yuan united the north under his rule, Yuan Shao would attack Cao Cao. If the plan succeeds, then half of China is under his control.

Cao Cao, although coming from despised and hated backgrounds, had  resources and assets. His paternal grandfather was a court eunuch, who was granted a sizeable amount of resources for his service. The resources his grandfather possessed fell into the hands of Cao Cao. Cao Cao using these resources, was able to field an army and establish his known territory. This, he was able to use to his advantage.

Although Cao Cao was not in a favorable geographical position, he did control Luoyang where the fractured Han government was based. He found and used the Han Emperor Xian as a puppet, controlling other warlords via the Emperor. Many aristocratic families were based in Cao Cao’s land and most went to Cao Cao. This is because since the Emperor was in the hands of Cao Cao, the nobles thought Cao Cao was trying to restore the Han Dynasty, even though Cao Cao was trying to establish his own. Consequently, the nobles granted Cao Cao resources and provisions for his future campaigns.

In summary, Cao Cao was able to fend off attacks by securing his alliances with other powerful warlords and use the emperor as a puppet to force the other warlords to bow before him. By doing so, he received aid from various noble families in the area. He turned his disadvantages into advantages and ultimately claimed hegemony in the north.