Britain achieved its all-red network and, with it, invulnerability. Everyone else, meanwhile, learned the cost of not having a secure network. In the opening days of the First World War, Britain cut Germany’s transatlantic cables—something it could easily do, as Germany did not control the territory around them. The Germans were then forced to use unreliable intermediaries to carry their messages, which opened them up to espionage. In 1917 the German foreign secretary Arthur Zimmermann sent a proposal to Mexico promising to help Mexico “reconquer the lost territory in Texas, New Mexico, and
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