Landships II

When putting together the article on WW1 electronic warfare I was fooled, I have to admit, by a combination of German and British mis-direction. I hope this sets the record straight.

When Britain cut the German sea bed telegraph cables in 1914 Germany did indeed revert to its wireless network, however this could not handle enough of the volume so an arrangement was made with Sweden for the Swedish transatlantic cable to carry a significant amount of German military and diplomatic traffic in contravention of the Swedish declaration of neutrality. At the US end it could be passed to various German organisations for recoding (if necessary) and routed onward via commercial US services. As the Swedish cable actually crossed Britain it was considered of vital importance by both Germany and Sweden for this traffic to be kept secret, as Britain would have been legally justified in cutting the cable. Consequently German intelligence ‘leaked’ stories exaggerating the amount of traffic carried by wireless.

Royal Navy intelligence had an intercept and code breaking unit called ‘room 40’ (based on their original location in the Admiralty). This was a sort of WW1 prototype of the WWII Bletchley Park operation and much about it was kept secret. Room 40 had found a way to tap the Swedish cable without making any physical incision into it. As a result they were fully aware of the German traffic on it, which they were decoding. It was decided (initially by a certain W S Churchill) that the value of the intelligence thus gained was greater than the damage that would have been caused to Germany by cutting the cable so this was kept very quiet. If Germany had learnt about this they would probably have used it to send deception messages. However when the cables to Mexico were intercepted it was thought most important to pass their contents on to the US authorities. To avoid blowing the secret of the cable tap an elaborate deception exercise was mounted to make it appear that British agents in the USA had done the interception. This involved changing details of the message to make it appear as if it had been decoded form the onward transmission rather than from the original. Exactly how this was done has not yet emerged but the deception was successful.