This article mentions the practice in WW1 and refers to it being done in WW2: https://www.atlasobscura.com/articles/knitting-spies-wwi-wwii https://www.atlasob

This article mentions the practice in WW1 and refers to it being done in WW2: https://www.atlasobscura.com/articles/knitting-spies-wwi-wwii https://www.atlasobscura.com/articles/knitting-spies-wwi-wwi... It also mentions the subject of OP's article too. I have seen an old piece of knitting from WW2 used to convey messages in a military museum in Portsmouth, UK. And this link includes details on how to do it: https://www.popsci.com/story/diy/secret-code-messages-knitting/ https://www.popsci.com/story/diy/secret-code-messages-knitti...