I sent Steve Harris, the author of "Duffy's War," some questions. Mike Hanlon, a World War I historian and Harris collaborator, sent some suggestions of what I could see about the Fighting 69th in France in World War I. In addition to the Château de Lunéville, he suggested: "Bathelémont-lès-Bauzemont, France -  Monument to first U.S. Killed in action in WWI in Bathelémont, France (48.69081, 6.51949) which is about 15km from Luneville.  The Rouge Bouquet site would be a little southeast of here I think." So we went there.