For September 22, some thoughts on the logistics of the enormous upcoming battle. From Chaplain Edwards in From Doniphan to Verdun:

The Germans knew we were to attack, but as late as September 22nd did not know whether the main attack was to be put on the Italian, French, British, or American front. And later they fully expected our advance to be made on Metz. We had nine divisions in line, and but three roads, one from Bethincourt to Montfaucon running diagonally across the direction of attack, and the territory of three divisions. 

The artillery, rolling kitchens, engineers supplies, etc., must have roads if they are to keep up with the infantry. They can not travel in mud. The Germans had three strong lines of defense, with several trenches to each one, the last line some distance back. When one remembers that we had to advance through woods and over hills, the progress is remarkable, and one looks with wonder at the traffic handled by the three roads…

Our regimental transport came overland; all the roads were overcrowded and congested. The American Army pay heavy rent for the use of French roads and repair them whenever damaged. Because of the overcrowded condition the transports did not reach us until the 22nd and 23rd. Rations were short. The men were tired, cold, wet, hungry and rations were very short. It is reported that the French entered heavy claims for food losses about this time.

From worldwar1.com:

The bulk of the forces engaged in the initial onslaught had to be transferred from the St. Mihiel Salient —- assaulted less than two weeks earlier —- to a new jump off line north and northwest of Verdun. This new section of the front extended thirty miles east to west . The re-shifting of forces in such a short period of time was one of the great accomplishments of the Great War. These logistics were planned and directed by Col. George C. Marshall establishing his reputation and preparing him to lead – in the distant future — American forces to victory in the Second World War.

Where was Robert today? See the timeline.