According to this web page (*) on July 29th the 47th US infantry regiment was with the 42nd infantry division and fought on the Ourcq river in Sergy, Aisne, near Fère-en-Tardenois:
On the extreme right, the 2d Battalion, 168th Infantry, was to lead the advance with the 3d Battalion, 47th Infantry, in support. It attacked about 8:30 a. m. from south of Sergy, met stubborn resistance and made no gain. The 3d Battalion, 47th Infantry, moved forward from the vicinity of La Cense with Companies I and L from right to left, leading, and Companies K and M in support. Company I was stopped in front of Sergy and fell back into the woods along the Ourcq River north of Ferme de La Motte. Company L drove the Germans from Sergy, passed through the town and reached the ridge to the-north. About 5 p. m. it withdrew to the western edge of the town.
As Ross Bankson belonged to company I, it seems likely that he took part in this attack, and died there.
Slightly west was the French 62nd infantry division. Detailed accounts of movements of French units during WWI (journaux des marches et opérations) are available online, here is what the 62e DI wrote for July 29th - note the references to "la 42e DIUS".
(*) it is actually a translation of a French page, itself written after a report by the American Battle Monuments Commission.