During the First World War, during the World War II, the President of the United States, Dr. W. Wilson, was President of Franklin D. Roosevelt Harry Truman became president after his death during the war.
During the American Civil War, Abraham Lincoln was president.
There were 4 president in Vietnam war. They are - John F. Kennedy, Lyndon Johnson, Richard Nixon and Gerald Ford
Richard Nixon was president during the liberation war of Bangladesh in 1971.