‘Boche?’ I asked.

‘Boche,’ he said.  ‘My God, we’re for it now.’

My heart had sunk like a stone, but I was fairly cool.  I looked at my watch and saw that it was ten minutes to eleven.

‘How many?’

‘Five,’ said Archie.  ‘Or there may be six—­not more.’

‘Listen!’ I said.  ’Get on to your headquarters.  Tell them that it’s all up with us if a single plane gets back.  Let them get well over the line, the deeper in the better, and tell them to send up every machine they possess and down them all.  Tell them it’s life or death.  Not one single plane goes back.  Quick!’

Archie disappeared, and as he went our anti-aircraft guns broke out.  The formation above opened and zigzagged, but they were too high to be in much danger.  But they were not too high to see that which we must keep hidden or perish.

The roar of our batteries died down as the invaders passed westward.  As I watched their progress they seemed to be dropping lower.  Then they rose again and a bank of cloud concealed them.

I had a horrid certainty that they must beat us, that some at any rate would get back.  They had seen thin lines and the roads behind us empty of supports.  They would see, as they advanced, the blue columns of the French coming up from the south-west, and they would return and tell the enemy that a blow now would open the road to Amiens and the sea.  He had plenty of strength for it, and presently he would have overwhelming strength.  It only needed a spear-point to burst the jerry-built dam and let the flood through . . .  They would return in twenty minutes, and by noon we would be broken.  Unless—­unless the miracle of miracles happened, and they never returned.

Archie reported that his skipper would do his damnedest and that our machines were now going up.  ‘We’ve a chance, sir,’ he said, ’a good sportin’ chance.’  It was a new Archie, with a hard voice, a lean face, and very old eyes.

Behind the jagged walls of the farm buildings was a knoll which had once formed part of the high-road.  I went up there alone, for I didn’t want anybody near me.  I wanted a viewpoint, and I wanted quiet, for I had a grim time before me.  From that knoll I had a big prospect of country.  I looked east to our lines on which an occasional shell was falling, and where I could hear the chatter of machine-guns.  West there was peace for the woods closed down on the landscape.  Up to the north, I remember, there was a big glare as from a burning dump, and heavy guns seemed to be at work in the Ancre valley.  Down in the south there was the dull murmur of a great battle.  But just around me, in the gap, the deadliest place of all, there was an odd quiet.  I could pick out clearly the different sounds.  Somebody down at the farm had made a joke and there was a short burst of laughter.  I envied the humorist his composure.  There was a clatter and jingle from a battery changing position.  On the road a tractor was jolting along—­I could hear its driver shout and the screech of its unoiled axle.