On July 8, 1950, General Douglas MacArthur was named commander-in-chief of UN forces in Korea.
"In 1949, the Chairman of the Joint Chiefs of Staff, General of the Army Omar Bradley, had predicted that "large scale combined amphibious operations ... will never occur again", but by July 1950, MacArthur was planning just such an operation.[298] MacArthur compared his plan with that of General James Wolfe at the Battle of the Plains of Abraham, and brushed aside the problems of tides, hydrography and terrain.[299] In September, despite lingering concerns from superiors, MacArthur's soldiers and marines made a successful landing at Inchon, deep behind North Korean lines. Launched with naval and close air support, the landing outflanked the North Koreans, recaptured Seoul and forced them to retreat northward in disarray.[300] Visiting the battlefield on 17 September, MacArthur surveyed six T-34 tanks that had been knocked out by Marines, ignoring sniper fire around him, except to note that the North Korean marksmen were poorly trained.[301]
On 11 September, Truman issued orders for an advance beyond the 38th parallel into North Korea. MacArthur now planned another amphibious assault, on Wonsan on the east coast, but it fell to South Korean troops before the 1st Marine Division could reach it by sea.[302] In October, MacArthur met with Truman at the Wake Island Conference, with Truman emulating Roosevelt's wartime meeting with MacArthur in Hawaii.[303] The president awarded MacArthur his fifth Distinguished Service Medal.[304] Briefly questioned about the Chinese threat, MacArthur dismissed it, saying that he hoped to be able to withdraw the Eighth Army to Japan by Christmas, and to release a division for service in Europe in January. He regarded the possibility of Soviet intervention as a more serious threat.[305]
A month later, things had changed. The enemy were engaged by the UN forces at the Battle of Unsan in late October, which demonstrated the presence of Chinese soldiers in Korea and rendered significant losses to the American and other UN troops. Nevertheless, Willoughby downplayed the evidence about Chinese intervention in the war. He estimated that up to 71,000 Chinese soldiers were in the country, while the true number was closer to 300,000.[306] He was not alone in this miscalculation. On 24 November, the Central Intelligence Agency reported to Truman that while there could be as many as 200,000 Chinese troops in Korea, "there is no evidence that the Chinese Communists plan major offensive operations."[307]
That day, MacArthur flew to Walker's headquarters and he later wrote:
For five hours I toured the front lines. In talking to a group of officers I told them of General Bradley's desire and hope to have two divisions home by Christmas ... What I had seen at the front line worried me greatly. The R.O.K. troops were not yet in good shape, and the entire line was deplorably weak in numbers. If the Chinese were actually in heavy force, I decided I would withdraw our troops and abandon any attempt to move north. I decided to reconnoiter and try to see with my own eyes, and interpret with my own long experience what was going on ...[308]
MacArthur flew over the front line himself in his Douglas C-54 Skymaster but saw no signs of a Chinese build up and therefore decided to wait before ordering an advance or withdrawal. Evidence of the Chinese activity was hidden to MacArthur: the Chinese Army traveled at night and dug in during the day.[306] For his reconnaissance efforts, MacArthur was nonetheless awarded the Distinguished Flying Cross and honorary combat pilot's wings.[308]
The next day, 25 November 1950, Walker's Eighth Army was attacked by the Chinese Army and soon the UN forces were in retreat. MacArthur provided the Chief of Staff, General J. Lawton Collins with a series of nine successive withdrawal lines.[309] On 23 December, Walker was killed when his jeep collided with a truck, and was replaced by Lieutenant General Matthew B. Ridgway, whom MacArthur had selected in case of such an eventuality.[310] Ridgway noted that MacArthur's "prestige, which had gained an extraordinary luster after Inch'on, was badly tarnished. His credibility suffered in the unforeseen outcome of the November offensive ..."[311]
Collins discussed the possible use of nuclear weapons in Korea with MacArthur in December, and later asked him for a list of targets in the Soviet Union in case it entered the war. MacArthur testified before the Congress in 1951 that he had never recommended the use of nuclear weapons. He did at one point consider a plan to cut off North Korea with radioactive poisons; he did not recommend it at the time, although he later broached the matter with Eisenhower, then president-elect, in 1952. In 1954, in an interview published after his death, he stated he had wanted to drop atomic bombs on enemy bases, but in 1960, he challenged a statement by Truman that he had advocated using atomic bombs. Truman issued a retraction, stating that he had no evidence of the claim; it was merely his personal opinion.[312][313][314]
In April 1951, the Joint Chiefs of Staff drafted orders for MacArthur authorizing nuclear attacks on Manchuria and the Shantung Peninsula if the Chinese launched airstrikes originating from there against his forces.[315] The next day Truman met with the chairman of the United States Atomic Energy Commission, Gordon Dean,[316] and arranged for the transfer of nine Mark 4 nuclear bombs to military control.[317] Dean was apprehensive about delegating the decision on how they should be used to MacArthur, who lacked expert technical knowledge of the weapons and their effects.[318] The Joint Chiefs were not entirely comfortable about giving them to MacArthur either, for fear that he might prematurely carry out his orders.[315] Instead, they decided that the nuclear strike force would report to the Strategic Air
Command."