Your editorial (Telling the truth in an age of information insecurity, 26 July) cites the 1917 Zimmermann telegram as a famous example of “spying on … enemy states”. But in fact the British intercepted traffic on the US State Department’s communications between Europe and Washington, which, by agreement, also carried German messages. So it was also a case of spying on “friendly” states (though British intelligence took effective steps to cover this up). As for the more important point – America’s entry into the first world war – this had everything to do with Germany’s unleashing unrestricted submarine warfare and rather little to do with the telegram and its cockeyed proposal to Mexico. At most, it may have stiffened President Wilson’s resolve, but it did not shake up American public opinion. Pro-German Americans (who were numerous) dismissed it as a fraud.
Emeritus Professor Alan Knight
St Antony’s College, Oxford
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