The Origin of the Black Riders
Many years ago I corresponded with Tolkien's son, a schoolmaster like myself. He said the Dark Riders in his novel were based on a real recurring nightmare from the First World War. Tolkien, riding a good cavalry horse, had somehow got lost behind the German lines, and, imagining he was behind his own trenches, rode towards a group of mounted cavalrymen standing in the shade of a coppice.
It was only when he drew nearer he realised his mistake for they German Uhlans, noted for their atrocities and taking no prisoners. When they saw him they set off in pursuit with their lances levelled at him. He swung his horse round and galloped off hotly pursued by the Germans. They had faster steeds but Tolkien's horse was a big-boned hunter.
They got near enough for him to see their skull and crossbone helmet badges. Fortunately for Tolkien (and us, his readers) he raced towards some old trenches which his horse, used to hunting, took in its stride. The Uhlans' horses weren't up to it and they reined in leaving Tolkien to get away to his own side.
He was terrified and the cruel faces of those Uhlans and their badges haunted him in nightmares for a long time afterwards. Years later, when he was writing his novel, the Dark Riders were the result of that terrifying chase.
Revd John Waddington-Feather, Shrewsbury