33rd President of the USA (1945–53). As Vice‐President, he automatically took office on Franklin Roosevelt’s death in 1945. One of his first actions was to authorize the use of the atom bomb against Hiroshima and Nagasaki in 1945 to end the war with Japan. At home Truman put forward an extensive social programme, which was largely blocked by Congress, although racial segregation in the armed forces and in federally funded schools was ended. His expression in 1947 of what became known as the Truman Doctrine (the principle that the USA should give support to countries or peoples threatened by Soviet forces or Communist insurrection) was seen by the Communists as an open declaration of the cold war. In 1948 his administration introduced the Marshall Plan of emergency aid to war‐shattered European countries and helped to establish NATO the following year. He later involved the USA in the Korean War.