Amphibious landings at Inchon by X Corps hit KPA forces from behind, allowing I Corps to breakout from the Pusan perimeter starting on 16 September. Four days later I Corps troops began a general offensive northward against crumbling KPA opposition to establish contact with forces of the 7th Infantry Division driving southward from the beachhead. Major elements of the KPA were destroyed and cut off in this aggressive penetration; the link-up was effected south of Suwon on 26 September. The offensive was continued northwards, past Seoul, and across the 38th Parallel into North Korea on 1 October. The momentum of the attack was maintained, and the race to the North Korean capital, Pyongyang, ended on 19 October when elements of the Republic of Korea Army (ROK) 1st Infantry Division and the US 1st Cavalry Division captured the city. The advance continued, but against unexpectedly stiffening resistance. The Chinese People's Volunteer Army (PVA) entered the war on the side of North Korea, making their first attacks in late October. By the end of October the city of Chongju, from the Yalu River border of North Korea, had been captured. IX Corps advanced in the center of the Army, with I Corps along the west coast and X Corps operating independently further east. Commanders hoped the offensive would end the war "by Christmas."