How cable infrastructure enabled British signals intelligence

How could Britain tap German telegraph traffic to the United States and South America during World War I?

Britain had helped lay much of the cable network and therefore knew where the relevant physical routes could be accessed.

British signals access rested on ownership and knowledge of physical infrastructure. British institutions had laid much of the cable network, so they knew where German-linked routes ran and where they could be intercepted. An intelligence advantage could come from control of seabed communications as well as from reading messages. In this short exchange, infrastructure knowledge becomes a form of wartime power.