I‘m with Brian, think it was a device to hold some sheets of note papers.The small lipp at the top inside seems to be there to hold sheets of paper. In these times the peoples often wrote journals or they needed a hard underlay to write down a notice when they were on a trip. The Material seems to be cast Zinc or Alpaka (Neusilber).
Concerning the Relief it may be a familar background or a souvenir of the Military.