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First World War successes

Almost starting from scratch, Britain built up a considerable Signals Intelligence effort during World War I.

A number of radio intercept stations were created, and a body of experienced cryptanalysts, linguists and radio traffic analysts enjoyed considerable success in breaking coded messages sent by the enemy.

Perhaps the most famous intelligence coup was Britain's intercept of a telegram sent by the German Foreign Minister Zimmermann in early 1917. The telegram stated that Germany was to undertake unrestricted submarine warfare against the USA and indicated that Mexico would be rewarded with the territories of Arizona, New Mexico and Texas if it joined the conflict!

It was one of the deciding factors in the USA joining the War on the side of the Allies.

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