
Operation Thunderbolt, launched on 25 January 1951, marked the first major counteroffensive under General Matthew Ridgway’s command of the U.S. Eighth Army during the Korean War. Following earlier Chinese offensives that had driven UN forces south of Seoul, the operation aimed to reclaim lost territory, inflict heavy casualties, and disrupt enemy plans. Ridgway’s cautious yet aggressive strategy involved reconnaissance in force, ensuring a measured advance while avoiding overextension.

Operation Thunderbolt (1951) map. © US Army
The offensive began with coordinated attacks by I Corps on the western front and IX Corps in the center. UN forces, including the 25th Infantry Division, 1st Cavalry Division, and the Turkish Brigade, pushed northward in multiple columns, encountering scattered Chinese and North Korean resistance. Early progress was deliberate, with troops methodically clearing roads and securing flanks while advancing toward the Han River. By the end of January, it was evident that enemy forces were retreating to regroup north of the river.

Operation Thunderbolt (1951) 1-11 February. © US Army
In early February, the operation expanded into a full-scale assault. I Corps captured critical positions near Seoul, including Kwanak Mountain, and secured the Kimpo Peninsula and Airfield, while IX Corps reached the Han River near Yangpyeong. Chinese forces mounted stubborn resistance in some areas, particularly around Yangpyeong, but failed to stop the UN advance. By 11 February, the UN had established a strong presence along the southern bank of the Han River, achieving the operation’s main objectives.
The success of Operation Thunderbolt demonstrated Ridgway’s emphasis on coordinated offensives and methodical advances. It forced the Chinese and North Koreans to abandon their positions south of the Han River and disrupted their ability to launch further offensives in the western sector. The operation inflicted significant enemy casualties while minimizing losses among UN forces.
Following this victory, Ridgway launched Operation Killer on 20 February 1951 to eliminate remaining enemy forces. Operation Thunderbolt marked a turning point in the war, shifting momentum back to the UN and laying the groundwork for future counteroffensives.