Mary Alsop King was the daughter of Charles King, a politician, newspaper editor, and president of Columbia College (now Columbia University) and Henrietta Liston Low. She was the granddaughter of Senator Rufus King, one of the signers of the U.S. Constitution in 1787. In Paris, she married William Henry Waddington a French statesman who was Prime Minister of France in 1879 and later became a diplomat, serving as the French Ambassador to Great Britain. She accompanied her husband to the Imperial court in Russia when he was appointed by the U.S. government as an Ambassador Extraordinary in 1883. Her personal letters and correspondence from this period were later published in Letters of a Diplomat’s Wife (1904). Mrs. Waddington also accompanied the Ambassador on two trips to Rome and was present in Paris during World War I. She recounted these experiences in two more well-known books, Italian Letters of a Diplomat’s Wife (1905) and My War Diary (1917).