The Liaodong Campaign led by Sima Yi, a key military figure in the state of Cao Wei during the Three Kingdoms period, was a significant military expedition aimed at conquering the northeastern territory of Liaodong. This campaign, which took place in the early 3rd century CE, was crucial for expanding Wei’s control and consolidating its power in the region, further shaping the dynamics of the Three Kingdoms era.

Sima Yi, renowned for his strategic acumen and as a formidable rival to Shu Han's Zhuge Liang, turned his attention to Liaodong, a region governed by Gongsun Yuan. Gongsun Yuan, initially a vassal of Wei, had declared independence and sought to establish his authority in Liaodong, posing a challenge to Wei's supremacy in the north.

The Liaodong Campaign was not only a response to Gongsun Yuan's defiance but also part of a broader strategy by Sima Yi to strengthen Wei's northern borders and secure key strategic and economic resources. Liaodong was significant for its strategic location, serving as a gateway to the Korean Peninsula, and its control was crucial for any power aspiring to dominate the region.

Sima Yi's campaign was marked by careful planning and strategic foresight. Understanding the challenges posed by the rugged terrain and the need for a sustained supply line, Sima Yi meticulously prepared for the expedition. He mobilized a large force, ensuring that it was well-equipped and provisioned for a prolonged campaign.

One of the key aspects of the Liaodong Campaign was the siege of Xiangping, the stronghold of Gongsun Yuan. The siege demonstrated Sima Yi's skill in siege warfare and his patience in military engagements. Despite the formidable defenses of Xiangping and the harsh weather conditions, Sima Yi's forces maintained a relentless assault on the city.

The fall of Xiangping was a turning point in the campaign. Gongsun Yuan's defeat and subsequent execution marked the end of his ambitions in Liaodong and the successful completion of Sima Yi's military objective. The conquest of Liaodong under Sima Yi's leadership significantly bolstered Wei's position in the north, extending its control and influence over a vast and strategically important region.

The successful Liaodong Campaign also reinforced Sima Yi's reputation as one of the most capable military leaders of his time. His victory in the northeast was not only a military triumph but also a testament to his strategic planning, logistical organization, and leadership skills.