After the landing at Inchon, X Corps attacked up the Korean peninsula on the left flank of Eighth Army. However, in early October it was withdrawn to prepare for another amphibious assault, this time at Wonsan on the eastern coast. This action proved to be a mistake as Republic of Korea Army (ROK) forces moving by land captured Wonsan on 11 October before the X Corps assault went in. The Chinese People's Volunteer Army (PVA) entered the war on the side of North Korea, making their first attacks in late October.