A towering history of the first Afghan War by bestselling historian William Dalrymple In the spring of 1839, the British invaded Afghanistan for the first time. Led by lancers in scarlet cloaks and plumed shakos, nearly 20,000 British and East India Company troops poured through the high mountain passes and re-established on the throne Shah Shuja ul-Mulk. On the way in, the British faced little resistance.