The Pershing family had its origins in the Alsace region, now part of France, but for centuries this area had been a bone of contention between France and the German states.
The French Republic had old grievances against the German Empire from the conquest of its eastern provinces of Alsace and Lorraine during the Franco-Prussian War at the start of the 1870s.
You see, Arp was among a number of artists and writers from around Europe who sought refuge in neutral Switzerland to escape the ravages of World War I. Arp was French and German and had grown up in Alsace.