‘What is that?’ asked someone.

‘It must be the mine we charged at La Boisselle. The biggest that has ever been.’

It was a good guess.  When, later in the battle, I stood by the crater of that mine and looked into its gulfs I wondered how many Germans had been hurled into eternity when the earth had opened.  The grave was big enough for a battalion of men with horses and wagons, below the chalk of the crater’s lips.  Often on the way to Bapaume I stepped off the road to look into that white gulf, remembering the moment when I saw the gust of flame that rent the earth above it.