 B. Russell, 17 Aug. 51. (3) MacArthur Hearings, pp. 3665-66.
General Marshall later said that MacArthur's statement of 24 March offering to negotiate with enemy leaders in the field was the culminating factor in President Truman's decision to relieve MacArthur. Marshall charged that this statement contained a thinly veiled hint that the enemy should either negotiate or the war would be carried to the Chinese mainland. He based this view on that portion of MacArthur's statement which said, "The enemy therefore must by now be painfully aware that a decision of the United Nations to depart from its tolerant effort to contain the war to the area of Korea through expansion of our military operations to his coastal areas and interior bases would doom Red China to the risk of imminent military collapse." 
The President found this to be a most extraordinary statement for a military commander of the United Nations to issue on his own responsibility. He construed MacArthur's statement as defiance of his orders as Commander in Chief and a challenge to his authority. Additionally MacArthur was, in the President's view, flouting the policy established by the United Nations. By this act General MacArthur had left the President no choice. He felt he could no longer tolerate MacArthur's insubordination.  President Truman nonetheless delayed a final decision; neither the general public nor General MacArthur was aware of President Truman's steadily mounting dissatisfaction.
But the stage had already been set for the final act. On 20 March General MacArthur, in reply to a personal letter from Joseph W. Martin, House of Representatives Minority Leader, sent a relatively mild commentary to the Congressman on American foreign policy. There was nothing new in what he said, nor was it said in a particularly inflammatory manner. MacArthur merely reiterated his views that the Asian theater was fully as important as the European and that the United States must prosecute the Asian war until victory was achieved. MacArthur later testified that the letter to Congressman Martin was, in his mind, so trifling a matter that he could scarcely recall it.  But it was no trifling matter to President Truman; and when Martin chose to make public the contents of the letter on 5 April 1951, the President reacted strongly and quickly. On 6 April, he called together his special assistant, Averell Harriman, Secretary of State Acheson, Secretary of Defense Marshall, and the chairman of the Joint Chiefs of Staff, General Bradley, and put the matter squarely before them. What should be done with General MacArthur? Harriman told Truman that MacArthur should have been fired two years ago.  But Secretary Marshall appreciated the possible repercussions that
 (1) Ltr., Secy. Marshall to Sen. Russell, 17 Aug. 51, in MacArthur Hearings, pp. 3655-66. (2) Statement of Gen. MacArthur, 24 Mar. 51, in MacArthur Hearings, p. 3541.
 Truman, Memoirs, II, 441-42.
 (1) MacArthur Hearings, p. 113. (2) See also MacArthur, Reminiscences, pp. 385-86 and 389.
 Harriman was referring to MacArthur's plea in 1949 that he was too busy when requested to return to the United States to discuss matters concerning the occupation of Japan, and to subsequent difficulty in convincing MacArthur to withhold approval from a bill of the Japanese Diet which was contrary to the approved economic policy for the occupation. See Truman, Memoirs, II, 447.
might come with MacArthur's dismissal and advised caution. He observed that if the President relieved General MacArthur it might be difficult to get pending military appropriations through Congress. General Bradley approached the question from the point of view of military discipline. He believed that MacArthur had acted in an insubordinate manner and that, consequently, he deserved to be relieved of his command. But he told Truman that he wished to talk with General Collins before making a final recommendation. Secretary Acheson believed that MacArthur should be relieved, but only after a unanimous decision to do so by the Joint Chiefs of Staff.
President Tr