After Zhou and Lin had negotiated Stalin's approval, Peng attended a conference in Beijing with Mao, Zhou, and Gao Gang on October 18, and they ordered the first wave of Chinese soldiers, in total more than 260,000 men, to cross into Korea on the night of October 19. On October 25, the PVA had its first confrontation with UN troops at Onjong and Unsan, and pushed the UN forces south of the Chongchon River by November 4 in the aftermath of First Phase Campaign. From November 24 to December 24, Peng directed 380,000 PVA troops to confront UN forces in the Second Phase Campaign, and he successfully recovered the area north of the 38th parallel. Despite his personal reservations, Peng then began an ambitious campaign to take the area south of the 38th parallel to fulfill Mao's political objectives for the war. About 230,000 Chinese soldiers crossed into South Korean territory on December 31 and captured Seoul as part of the Third Phase Campaign but were forced to evacuate it with heavy losses on March 14, 1951 as the UN forces counterattacked during the course of Fourth Phase Campaign. Peng launched a final Fifth Phase Campaign from April 22 to June 10 to retake Seoul with 548,000 Chinese troops, but it failed, and the Korean War came to a standstill just north the 38th parallel. In the evaluation of US Army's official Korean War historian Roy Edger Appleman, Peng's performances in the war were unremarkable in terms of military talents despite his aggressiveness and leadership skills. During the Cultural Revolution, Red Guards claimed that Peng's successful campaigns, from October to December 1950, were fought under Mao's direction but that his unsuccessful campaigns, from January to May 1951, were organized by Peng against Mao's instructions. Modern scholars reject that interpretation and credit Peng with both the successes and the failures of the war.