WWI~WWII Military Handless Watchman Mug

Believed to be an early WWI~WWII watchmans handless mug for coffee, soup, or for a good lather for a good shave.

Bottom appears to read: ...cimmel, China, USAMC

Not sure what "USAMC" stands for - US Army Medical Component? USA Marine Corps? US Army Materiel Command?

Also have a similar Corning (milk) glass mug with the Glass- or Hornblower Trademark on the bottom, and the other a Shenango China watchmans mug.

Measurements:
> Base, 2.5"
> Height, 3.5"
> Mouth Opening, 3"
> Inner Depth, 3"
> Weight, 1 lb 3.7 oz

Any help identifying the manufacturer, age, and info on this mug is appreciated.