In the early months of 1839, India’s governor-general, Lord Auckland, dispatched a 10,000-strong British army across the Indus and up the mountainous valleys towards Kabul, to replace the Afghan ruler (rumoured to be friendly to the Russians) with a weak exile called Shah Shuja. The awful finale of the expedition – a retreat back to India in which only one Briton survived out of the 16,500 who began it
