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 Britain 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 and included in Portugal's "
Rose-coloured Map".