Kitchener was appointed Lord Roberts' chief of staff in South Africa on 18 December 1899, and participated in the execution of Roberts' flanking march round the Boer positions in the southern Orange Free State in February, 1900, and contributed significantly to the advances through Bloemfontein, Johannesburg and Pretoria, succeeding Roberts on 29 November. In the effort to control the region, politically and militarily, Kitchener instituted, particularly as a means of crushing the Boer guerrilla forces, a system of concentration camps which were meant to eliminate the guerilla support areas, but which led to uncountable deaths and immense cruelty against civilians. Eventually the guerrilla fighters surrendered and complete British Imperial sovereignty was imposed. In 1911-14, Kitchener was Viceroy of Egypt and the Sudan, on leave in England at the outbreak of the Great War. He accepted appointment as the non-political Secretary for War in July, 1914, and supervised the expansion of home industry to support the huge volunteer army for which he was largely responsible in creating, but was subsequently relieved of his responsibility in May 1915.
Kitchener's strategic authority was removed by the Cabinet during his visit to Gallipoli in November, 1915. Remaining in the Cabinet, Kitchener was sent on a mission to Russia and while en route aboard the cruiser HMS Hampshire, was drowned when the Hampshire struck a mine and sank off the Orkney Islands on 5 June 1916.