Gallatin himself was born on July 23, 1881, in the country house of his maternal grandmother, Cornelia Lansdale Ewing, which was located in Villanova, Pennsylvania. He attended schools there and in New York, including the Cutler preparatory school and the New York Law School both in New York City. He did not take the bar exam, however, and later said "I don't know why the devil I did it. I think an abstract artist is of more value to the community than a lawyer." As he matured he mixed freely in New York society, frequenting the opera and charity balls. In 1907 he co-founded the Motor-Car Touring Society. He belonged to the Union Club, the Pilgrims Society, the Society of Colonial Wars, and was the sole American member of the French branch of the Society of the Cincinnati. After the United States entered World War I he signed up as an ensign in the Naval Coast Defense Reserve. He also chaired two committees: the Committee on Exhibitions and Pictorial Publicity of the United States Government Committee on Public Information and the Committee on Arts and Decorations of the Mayor's Committee on National Defense. The first dealt with art propaganda and led to the publication of his book, Art and the Great War (New York, E.P. Dutton & Company, 1919). The second advised artists on contributing work to the war effort. In December, 1918, Gallatin organized an Allied War Salon under the auspices of both committees. The exhibition took place at the American Art Association, Madison Square South, New York. Duncan Phillips of the American Federation of Arts and Augustus Vincent Tack of the Liberty Loan Committee were co-organizers. It included a large number of paintings, drawings, posters, and other works by the official and unofficial artists of the allied countries. Gallatin was a trustee of New York University and a patron of and donor to numerous art organizations including New York University, the Museum of Modern Art, American Abstract Artists, Museum of the City of New York, and the Berkshire Museum.
