雙子星
The Ultimatum refers to a memorandum sent to the Portuguese Government by Lord Salisbury on 11 January 1890 in which he demanded the withdrawal of the Portuguese troops from Mashonaland and Matabeleland (now Zimbabwe) and the area between the Shire river north of the Ruo and Lake Nyasa (including all the Shire Highlands), where Portuguese and British interests in Africa overlapped. It meant that Britain was now claiming sovereignty over territories, some of which had been claimed by Portugal for centuries. There was no dispute regarding the borders of Angola, as neither country had effectively occupied any part of the sparsely populated border area.