Most Americans in the 1950s did not expect that Harry Truman would become one of their most highly regarded presidents. By 1952, just before he announced his decision not to run again, only 25% of the people thought he was doing a good job. Within a decade, however, most American historians regarded him as one of the nation's greatest presidents.
Obviously, Truman was not so effective in domestic affairs as his predecessor, Franklin Roosevelt, had been in the 1930's.
Truman's record in foreign affairs, while also flawed, was more significant. He effectively developed a larger role for the nation in world affairs than it had played before World War II. Truman's policy helped the recovery and reconstruction of western Europe, but more importantly they help contain the rapid spread of Communism, such policies were the hallmark of the cold war.
Seeking to carry out Roosevelt's policies, Truman brought to fruition the plans for the unconditional surrender of Germany, which came on May 8, 1945 and the establishment of the United Nations. He attended the UN founding conference in San Francisco in late April. Truman made the decision to use atomic bombs against Japan, believing that they would end the war quickly, save lives, and place the United States in a position to revolutionize Japanese life. Two bombs dropped on Hiroshima and Nagasaki, coupled with Russia's declaration of war against Japan, brought the war to an end on August 14, 1945.
Some persons have argued that Truman used the bomb to influence the Russians rather than the Japanese, but they have demonstrated only that he and some of his aides hoped that this new evidence of American power would restrain the Russians at the same time that it accomplished American objectives in Japan. By August 1945, Truman had become more critical of the Russians than Roosevelt had been. As time passed in 1945, Russian efforts to dominate eastern Europe became more obvious and alarming to American officials, and the need for Russian help, which had influenced Roosevelt so much, significantly declined as Germany and Japan were defeated and the United Nations was established.
Given the Russian military presence and determination in Eastern Europe, Truman had little opportunity to be effective there, but he found larger opportunities in southern and western Europe. Economic and political weaknesses seemed to give the Russians a chance to extend their influence into the region, but a series of American moves from 1947 to 1949 promoted economic improvements, strengthened non-Communist governments, and contributed to the containment of Communist groups.
TRUMAN DOCTRINE
The first significant application of the containment doctrine came in the Easter Mediterranean. Great Britain had been supporting Greece, where communist forces threatened the ruling monarchy in a civil war, and Turkey, where the Soviet Union pressed for territorial concessions and the right to build naval bases on the Bosporus. In 1947 Britain told the United States that it could no longer afford such aid. Quickly, the U.S. State Department devised a plan for U.S. assistance. But support for a new interventionist policy, Senate leaders such as Arthur Vandenberg told Truman, was only possible if he was willing to start 'scaring the hell out of the country' Truman was prepared to do so. On Wednesday, March 12, 1947 President Truman addressed the Congress.
One way of life is based upon the will of the majority, and is distinguished by free institutions, representative government, free elections, guaranties of individual liberty, freedom of speech and religion, and freedom from political oppression.
The second way of life is based upon the will of a minority forcibly imposed upon the majority. It relies upon terror and oppression, a controlled press and radio, fixed elections, and the suppression of personal freedoms.

Then came the dramatic sentence that set forth what was to become known as the 'Truman Doctrine.' The president said, 'I believe that it must be the policy of the United States to support free peoples who are resisting subjugation by armed minorities or by outside pressures.' The immediate objective of the policy was to send U.S. aid to anti-Communist forces in Greece and Turkey, but it was later expanded to justify support for any nation that the United States government believed was threatened by Communism during the Cold War period.
Marshall Plan
Containment also called for extensive economic aid to assist the recovery of war-torn Europe. With many of the region's nations economically and politically unstable, the United States feared that local communism parties, directed by Moscow, would come to power. On June 5, 1947, George ...