Pulitzer Prize winning historian and adviser to US President John F Kennedy Arthur M Schlesinger Jr has died aged 89 of a heart attack in New York.
Mr Schlesinger was an influential voice in liberal American politics
Mr Schlesinger helped define America's Cold War liberalism after World War II.
He served in the OSS - the forerunner of the CIA - during WWII before taking up a dual role as political adviser and writer of prize-winning histories.
He advocated defending American ideals abroad but in 2004 wrote a book critical of the war in Iraq.
Mr Schlesinger won his first Pulitzer Prize in 1945 at age 28 for a best-selling history of US President Andrew Jackson, The Age of Jackson.
He was often considered the epitome of the American intelligentsia, favouring bow ties and wearing horn-rimmed glasses.
In the 1950s he worked on the unsuccessful presidential campaigns of Democratic candidate Adlai Stevenson. He was an adviser and speech writer to John F Kennedy's successful 1960 run for the presidency.
He advised President Kennedy against the failed Bay of Pigs invasion of 1961.
After serving as an a special adviser in the Kennedy White House he won his second Pulitzer in 1965 for A Thousand Days: John F Kennedy in the White House.
He continued to write political histories and newspaper opinion pieces. In 2004 he criticised the presidency of George W Bush in War and the American Presidency.
He was born on 15 October 1917 in Columbus, Ohio.