Royal Can Opener Nice WWI The lid appears to say

The lid appears to say Hasse 0

This is actually an accessory to the Bakelite Wehrmacht lantern and has its own spot in the main lantern box

Vintage WWII "73 Questions and Answers About the WAAC" (Women's Army Auxiliary Corps) booklet

they were forced to sell the company for a fraction of its value in 1938

Royal Can Opener Nice WWI The lid appears to sayPeriod German Royal can opener that works completely different than American types. You force the cutter through the can, then drag it around the edge. This design was popular in Germany for a long time. It is an earlier style, made from steel and wood. This one shows some age, but not a lot of use. The teeth are still quit sharp and the cutting blade is also in good condition. It needs a little cleaning.