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Everett True believes in second chances (June 28, 1919)
(lemmy.world)
On June 28, 1919, the day this was printed, the Treaty of Versailles was signed in France ending the state of war between Germany and the Allied Powers of World War I. That's the context for the "hun mine-layer" comment.
It sounds to me like this is more referencing their nomadic aspect. A nomadic people laying mines would be a great idiom.