Corpses were the cause. If you have ever looked at a lapel in November and wondered why the poppy is the flower pinned to it, then the answer is corpses, and chemistry. Today, the poppy is associated with Flanders fields. It shouldn’t be: the soil is too poor for them. But, from 1914 onwards, there was in the corner of that foreign field a richer dust concealed. Or, to be more precise, there were corpses: rotting, festering, fly-blown corpses, decomposing and covering the mud in a “plastering slime” as Siegfried Sassoon, a poet, wrote. The soldiers were repelled; the poppies flourished. “In Flanders fields the poppies blow,” wrote one soldier in 1915, “Between the crosses, row on row”.