Pach, Walter

But any further participation by Duchamp in French exhibits ceased early in 1913. In that year, his work appeared—with much fanfare—on the other side of the Atlantic, in the famous Armory Show mounted in New York from February to March of 1913. Duchamp left France early in the summer of 1915, taking up a more or less permanent residence in America, where he immediately gained the kind of critical notoriety that stubbornly eluded him in Paris. In part, this important exodus was due partly to an invitation extended to Duchamp by an American painter, Walter Pach, and partly, at the very beginning of World War I, to an understandable desire to avoid being called once again to the French colors. In those months, it was obvious that uniformed males led violent and short lives. ... 

Duchamp, M. Affectueusement [et] Amicalement, Marcel Letters from Marcel Duchamp to Suzanne Duchamp and Jean Crotti [and] to Walter Pach. Ed. E Naumaim. Archives of American Art Journal Tl (1982) 2-19 29 (1989) 36-50. 

Eugene Delacroix, The Journal of Eugene Delacroix, trans. Walter Pach (New York Crown, 1948), p. 510. 

---