In 1867, Markham was selected to accompany Sir Robert Napier's military expeditionary force to Abyssinia, as the expedition's geographer. This force was despatched by the British government as a response to actions taken by the Abyssinian King Theodore. In 1862, the king had written to the British government requesting helping modernize his nation, and proposing the appointment of an ambassador to which the British had previously suggested. Unwilling to risk monopoly of cotton in Egypt, the British government did not reply. The king reacted to this slight and other snubs by seizing and imprisoning the British consul and his staff, and ordered the arrest and whipping of a missionary who had insulted the king's mother. A belated reply to the king's letter resulted in the capture and incarceration of the deputation that brought it. After efforts at conciliation failed, the British decided to settle the matter by sending a military expedition. Because the geography of the country was so little known, it was decided that an experienced traveller with map-making skills should accompany the force, hence Markham's appointment.