Hermann’s freckled face was set in a grimace of anxiety, and he muttered to Erik in an undertone no one else could hear: ‘This is stupid!’

‘You should know better than to say that – you were in the Hitler Youth,’ said Erik quietly. ‘Have faith in the Führer.’ But he was not angry enough to denounce his friend.

When they did move it was painfully uncomfortable. They sat on the hard wooden floor of an army truck as it bounced over tree roots and swerved around potholes. Erik longed for battle just so that he could get out of the damn truck.

Hermann said more loudly: ‘What are we doing here?’

Their boss, Dr Rainer Weiss, was sitting on a real seat beside the driver. ‘We are following the orders of the Führer, which are of course always correct.’ He said it straight-faced, but Erik felt sure he was being sarcastic. Major Weiss, a thin man with black hair and spectacles, often spoke cynically about the government and the military, but always in this enigmatic way, so that nothing could be proved against him. Anyway, the army could not afford to get rid of a good doctor at this point.

There were two other medical orderlies in the truck, both older than Erik and Hermann. One of them, Christof, had a better answer to Hermann’s question. ‘Perhaps the French aren’t expecting us to attack here, because the terrain is so difficult.’

His friend Manfred said: ‘We will have the advantage of surprise, and will encounter light defences.’

Weiss said sarcastically: ‘Thanks for that lesson in tactics, you two – most enlightening.’ But he did not say they were wrong.

Despite all that had happened there were still people who lacked faith in the Führer, to Erik’s amazement. His own family continued to close their eyes to the triumphs of the Nazis. His father, once a man of status and power, was now a pathetic figure. Instead of rejoicing in the conquest of barbarian Poland, he just moaned about ill-treatment of the Poles – which he must have heard about by listening illegally to a foreign radio station. Such behaviour could get them all into trouble – including Erik, who was guilty of not reporting it to the local Nazi block supervisor.

Erik’s mother was just as bad. Every now and again she disappeared with small packages of smoked fish or eggs. She said nothing in explanation, but Erik felt sure she was taking them to Frau Rothmann, whose Jewish husband was no longer allowed to practise as a doctor.

Despite that, Erik sent home a large slice of his army pay, knowing his parents would be cold and hungry if he did not. He hated their politics, but he loved them. They undoubtedly felt the same about his politics and him.

Erik’s sister, Carla, had wanted to be a doctor, like Erik, and had been furious when it was made clear to her that in today’s Germany this was a man’s job. She was now training as a nurse, a much more appropriate role for a German girl. And she, too, was supporting their parents with her meagre pay.