Fourth Field Army
Nevertheless, the Chinese communists and the resuscitated North Korean Army pushed United Nations forces southward from Seoul. They were unsupported by the Chinese Air Force, which maintained air superiority in northwestern Korea. On 31 December, the communist ground forces launched an all-out offensive. Unfortunately for them, the first five days of 1951 offered crystal clear flying weather. On 1 and 2 January, the UN's Tactical Air Control Center handled fighter-bomber flights arriving over the front lines at ten-minute intervals; 60% of these flights struck with close air support for UN forces. By 3 January, most tactical sorties were seeking targets of opportunity well behind communist lines. By 5 January, the USAF estimated it had killed nearly 8,000 communist soldiers in five days; 8th Army thought the casualty count was twice that. By 25 January 1951, the UN forces had been pushed back to a line somewhat north of the 37th parallel of latitude. At dawn that day, UN troops counterattacked. An 8th Army intelligence report issued the following day estimated communist casualties at 38,000 killed; 18,820 of those dead were credited to tactical air strikes. Without their own air support, the communists had begun their withdrawal to the 38th parallel on 15 January. "Mosquito" FACs of the 6147th TCG began spotting concentrations of retreating communist troops on 30 January. Approximately 1 February 1951, General Peng Dehuai relieved an ailing Lin Biao from command. On 16 February, Peng ordered the Fourth Field Army to hold a line approximating the 38th parallel until May, when they were expected to counterattack.