There is an interesting article about Electronic Warfare in WW1 on the Landships website, in which Robert Robinson describes a somewhat obscure aspect of the Great War.

There is a common misconception that electronic warfare began with the Second World War but, even if it was not so labelled, it played a significant part in the First World War at both a strategic and a tactical level.

Fans of sound mirrors might be interested in the tale of how the Eiffel Tower was used to confuse Zeppelins.