Excellent summary of Combat Activities In Korea, 20 April Through 20 May 1951

In April 1951 the Chinese Peoples Volunteer Army (PVA) launched the first phase of its Spring Offensive with three field armies totaling 700,000 men against the U.S. I Corps and US IX Corps.

In May 1951, the PVA and Korean People’s Army(KPA) launched the second phase of their Spring Offensive against the Republic of Korea (ROK) forces and US X Corps in the east.

Although initially successful, PVA and KPA advances were halted by late May.

At the end of May 1951, US Eighth Army counterattacked the overextended, exhausted PVA/KPA forces, inflicting heavy losses.

Main source: Chinese Spring Offensive