John A. Herbers was serving in France at the time of the signing of Armistice.
From the 1983 Halbur Centennial book.

Departure August 18, 1918, at Hoboken, New Jersey, on the U.S.S. George Washington (ID-3018)
Unit Company "A" 19th Machine Gun Battalion
Departure June 12, 1919, from Brest, France on the U.S.S. Imperator (ID 4080)
Arrival June 20, 1919, at Hoboken, New Jersey
Residence Manning, Iowa - father, John Herbers
Unit Headquarters Detachment, 7th Division
Rank Private
Service Number 490192