The lorries rumbled on through the night. Aimee tried to sleep but the soldiers who were staying in the attic and cellar of the farmhouse scraped and clumped their boots on stairs and floors, shouted and cursed one another as they returned for a rest. Aimee was pleased she didn’t understand their swearing.

The next morning it was drizzling with rain and the fields were turning muddy.

Master DuPont arrived with news. ‘A British shell missed the railhead and destroyed a cottage. Old Madame Leclerc was killed. The German soldiers cleared the rubble but they’ll leave the burial to our priest, Father Gaston.’

Aimee headed through the woods towards the river to find some acorns for the next message. Each acorn in the broomstick stood for a German tank. They had very few tanks – and they were snail-slow and broke down often – but the British wanted to know what their soldiers would face.

There was a soft chopping coming from further down the path towards the River Somme. Aimee walked softly down the damp path to spy on the enemy. A soldier in a uniform the colour of wood-smoke was cutting into a willow tree and peeling off the bark. He placed the strips carefully into a rotting leather bucket. As he turned the soldier looked up. It was the boy who’d been helping the German doctor. What did he call himself? Marius, was it?

The soldier gave a shy smile. ‘Why are you killing that tree?’ Aimee spat at him. He looked confused. She repeated it in Latin and the cloud cleared from the boy’s face.

‘I am making a drug to cure our sick men. They have flu. The sickness is killing more of our men than British guns.’

‘The war will end quicker then,’ the girl replied coldly.

Marius shrugged. ‘It cannot go on much longer. Back in Germany the people are starving – that’s why I joined the army. The British battleships are stopping our food ships from getting through. I left home so there was one less mouth for my mother to feed.’

‘What about your father?’

‘Missing after the battle at Verdun,’ the boy said quietly. ‘We hope he’s a prisoner.’

‘You’re saying you left home to eat, not to kill?’ she asked. It explained why he was so pale and thin.

‘I left to help with the sick. I can’t even fire a gun. I haven’t been trained.’

‘If you’re all so hungry why don’t you just go home and leave us in peace?’ Aimee asked more gently.

‘A lot of our soldiers are deserting because they know we are losing. I took this uniform from a soldier who’d run away from the fighting. The men are tired and hungry and this sickness is the last dagger in our hearts.’

‘Then why doesn’t King Wilhelm give up?’