Lyndon Baines Johnson , often referred to as LBJ, was the thirty-sixth President of the United States, serving from 1963-1969. A Democrat, Johnson succeeded to the presidency following the assassination of President Kennedy, and after completing Kennedy's term was elected President in his own right in a landslide victory in the 1964 Presidential election. Johnson was a major leader of the Democratic Party and as President was responsible for designing the "Great Society" legislation that included civil rights laws, Medicare , Medicaid , aid to education, and the "War on Poverty." Simultaneously, he escalated the American involvement in the Vietnam War, from 16,000 American soldiers in 1963 to 550,000 in early 1968.