As Lord Roberts' army moved out of Bloemfontein on that great march to Pretoria, which it will be our business to record in a succeeding chapter, a small column in the western field of war struck north from Kimberley upon an even more arduous and incalculably more dangerous enterprise the relief of Mafeking. Colonel Mahon, an officer of Egyptian renown, was in command, and with him rode a force of picked men.