‘Five minutes, Baron,’ the man replied. ‘We’re changing the oil and...’

‘In five minutes a hundred men could be dead.’ He looked around the airfield. ‘What is ready to go now?’

‘The Albatross J2, Baron.’

The pilot was pulling on a leather coat and flying helmet as he marched across to one of the dull planes with two wings and two seats. He looked over his shoulder at Marius and called, ‘The British fighters will be ready to defend the balloon. I can’t fight them in this bus. I need a gunner in the rear seat. You can be my gunner and show me where you saw that balloon.’

Marius hardly had time to gather his breath. He ran after the pilot as mechanics scurried around to make the plane ready for take-off. ‘I don’t think I can fire a machine gun.’

‘Of course you can. Every soldier learns it in basic training.’

Marius almost blurted that he had done no basic training. He had no right to be there. But the pilot – the Baron – was already climbing on to the wing of the plane. ‘You know the plan,’ he called to the other pilots who were heading for the small planes with three wings. They answered with salutes. He then turned to the boy. ‘Where are we going?’ he asked.

‘Five kilometres north-west of here. Near the town of Bray.’

‘I know it,’ the pilot said as he hauled himself into the cockpit and a mechanic helped Marius into the seat behind the pilot. The pilot pressed switches and gave a thumbs-up sign to one of the ground crew who swung the propeller round.

The engine rasped, sputtered and sparked into life. Marius struggled back into his boots as the plane turned round and began to race and bump over the grassy field. The wooden frame creaked and groaned then the rattling of the wheels suddenly stopped as it lifted into the air.

The wind took the breath out of Marius’s body and the speed pressed him back in his seat. Fumes of petrol and castor oil filled his nose while the wind sang through the wires that held the plane together.

As they soared towards the clouds the pilot levelled off and circled. Marius saw the balloon at the same time as the man in front of him. From the skies it appeared a much smaller elephant than it had looked from the woods and Marius wondered how they could hit such a tiny target.

The pilot nudged the controls and the plane began a flat run towards it a kilometre away. Suddenly brown smoke mushrooms appeared in the air beside them and splinters of shell spattered against the plane – the British gunners on the ground were ready for this sort of attack and were firing at them. The pilot held steady and the balloon began to loom larger. Marius strained forward and saw two pale faces staring at him from the basket.