At the start of the 19th century, the Portuguese presence in Africa south of the equator was limited in
Angola to
Luanda and
Benguela and a few outposts, the most northerly of which was
Ambriz and in
Mozambique to the
Island of Mozambique, several other coastal trading posts as far south as
Delagoa Bay and the virtually independent
Prazo estates in the Zambezi valley. The first challenge to Portugal's wider claims came from the
Transvaal Republic, which in 1868 claimed an outlet to the Indian Ocean at Delagoa Bay. Although in 1869, Portugal and the Transvaal reached agreement on a border under which all of Delagoa Bay was Portuguese, the UK then lodged an objection, claiming the southern part of that bay. The claim was rejected after
arbitration by
President MacMahon of
France. His award made in 1875 upheld the border agreed in 1869. A second challenge came from the foundation of a German colony at
Angra Pequena, now known as
Lüderitz in Namibia in 1883. Although there was no Portuguese presence there, Portugal had claimed it on the basis of discovery. A far more serious dispute arose in the area of the Zambezi valley and
Lake Nyasa. Portugal occupied the coast of Mozambique from the 16th century, and from 1853 the Portuguese government embarked on a series of military campaigns to bring the Zambezi valley under its effective control. During the 1850s, the areas south of Lake Nyasa (now
Lake Malawi) and west of the lake were explored by
David Livingstone and several
Church of England and Presbyterian missions were established in the
Shire Highlands in the 1860s and 1870s. In 1878, the
African Lakes Company was established by businessmen with links to the Presbyterian missions. Their aim was to set up a trading company that would work in close cooperation with the missions to combat the slave trade by introducing legitimate trade and develop European influence in the area. A small mission and trading settlement was established at
Blantyre in 1876. Portugal attempted to assert its African territorial claims through three expeditions led by
Alexandre de Serpa Pinto, first from Mozambique to the eastern Zambezi in 1869, then to the
Congo and upper Zambezi from Angola in 1876 and lastly crossing Africa from Angola in 1877–1879. These expeditions were undertaken with the intention of claiming the area between Mozambique and Angola. Following Serpa Pinto's explorations, the Portuguese government in 1879 made a formal claim to the area south and east of the
Ruo River (the present south-eastern border of
Malawi) and, in 1882, occupied the lower
Shire River valley as far as the Ruo. The Portuguese then asked the British government to accept this territorial claim, but the opening of the
Berlin Conference of 1884–85 ended the discussions. Portugal's efforts to establish this corridor of influence between Angola and Mozambique were hampered by one of the articles in the General Act of the Berlin Conference which required
uti possidetis of areas claimed rather than historical claims based on discovery or those based on exploration, as Portugal had used. To validate Portuguese claims, Serpa Pinto was appointed as its consul in Zanzibar in 1884 and given the mission of exploring the region between Lake Nyasa and the coast from the Zambezi to the
Rovuma River and securing the allegiance of the chiefs in that area. His expedition reached Lake Nyasa and the Shire Highlands but failed to make any treaties of protection with the chiefs in territories west of the lake. At the northwest end of Lake Nyasa around
Karonga, the African Lakes Company made, or claimed to have made, treaties with local chiefs between 1884 and 1886. Its ambition was to become a
chartered company and control the route from the lake along the Shire River. Despite the outcome of the Berlin Conference, the idea of a trans-African Portuguese zone was not abandoned; to help to create it, Portugal signed treaties with France and Germany in 1886. The German treaty noted Portugal's claim to territory along the course of the Zambezi linking Angola and Mozambique. Following the treaties, the Portuguese foreign minister prepared what became known as the
Rose Coloured Map, representing a claim stretching from the Atlantic to the Indian Ocean. As late as 1888, the British
Foreign Office declined to offer protection to the tiny British settlements in the Shire Highlands. However, it did not accept the expansion of Portuguese influence there, and in 1889, it appointed
Henry Hamilton Johnston as British consul to Mozambique and the Interior, and instructed him to report on the extent of Portuguese rule in the Zambezi and Shire valleys. He was also to make conditional treaties with local rulers outside Portuguese control. The conditional treaties did not establish a British protectorate but prevented the rulers from accepting protection from another state. ==Ultimatum==