What were the original words, and how and why did it change?
Answer: The original words were, “I pledge allegiance to my Flag and the Republic for which it stands, one nation, indivisible, with liberty and justice for all.”
In 1923 and 1924 the National Flag Conference, under the leadership of the American Legion and the Daughters of the American Revolution, changed the words, ‘my Flag,’ to ‘the Flag of the United States of America.’
In 1954, Congress added the words, ‘under God,’ to the Pledge. Some accounts say this followed a campaign by the Knights of Columbus, and some say President Eisenhower encouraged the change due to the threat of Communism at the time.
So the Pledge now is, “I pledge allegiance to the flag of the United States of America, and to the republic for which it stands, one nation under God, indivisible, with liberty and justice for all.”