The British knew this-they had intelligence, too. Their counterplan was to slow Rommel's response by disrupting his communications. Night and day, British and American bombers pounded roads and railways, bridges and tunnels, stations and marshaling yards. And the Resistance blew up power stations and factories, derailed trains, cut telephone lines, and sent teenage girls to pour grit into the oil reservoirs of trucks and tanks.

Dieter's brief was to identify key communications targets and assess the ability of the Resistance to attack them. In the last few months, from his base in Paris, he had ranged all over northern France, barking at sleepy sentries and putting the fear of God into lazy captains, tightening up security at railway signal boxes, train sheds, vehicle parks, and airfield control towers. Today he was paying a surprise visit to a telephone exchange of enormous strategic importance. Through this building passed all telephone traffic from the High Command in Berlin to German forces in northern France. That included teleprinter messages, the means by which most orders were sent nowadays. If the exchange was destroyed, German communications would be crippled.

The Allies obviously knew that and had tried to bomb the place, with limited success. It was the perfect candidate for a Resistance attack. Yet security was infuriatingly lax, by Dieter's standards. That was probably due to the influence of the Gestapo, who had a post in the same building. The Geheime Staatspolizei was the state security service, and men were often promoted by reason of loyalty to Hitler and enthusiasm for Fascism rather than because of their brains or ability. Dieter had been here for half an hour, taking photographs, his anger mounting as the men responsible for guarding the place continued to ignore him.