Every merchant attack gives a raider away

Once Graf Spee left her waiting area, the ship could begin attacking the unescorted trade routes off Brazil. British officers had expected attacks near the richer River Plate or Freetown routes, so the approach to Brazil placed Graf Spee on a secondary route instead. The Royal Navy lacked enough escorts to convoy both the North Atlantic and the distant South Atlantic routes, leaving hunter groups and locally stationed cruisers to cover an immense area. Merchant ships also tried to stay within the emerging Pan-American Neutrality Zone, although on 29 September the formal zone had not yet been declared. Each victim could transmit information that narrowed the search. Like a submarine that has revealed its position, a surface raider lost much of its protection once it attacked, making concealment part of its effective armament.