The 1890 British Ultimatum was an ultimatum by the British government delivered on 11 January 1890 to Portugal. The ultimatum forced the retreat of Portuguese military forces from areas which had been claimed by Portugal on the basis of historical discovery and recent exploration, but which the United Kingdom claimed on the basis of effective occupation. Portugal had attempted to claim a large area of land between its colonies of Mozambique and Angola including most of present-day Zimbabwe and Zambia and a large part of Malawi, which had been included in Portugal's "Rose-coloured Map".