The 1925 German Second Ultimatum to Portugal was an oral ultimatum presented to Manuel II de Braganza, King of Portugal, by Alfred von Tirpitz, Reichskanzler of the German Empire, on June 1st, 1925. The Germans demanded that Portugal give up the Nyasaland (German: Njasaland), which had been occupied by Portuguese colonial forces during the ongoing British Revolution. It's known as such due to the First Ultimatum of 1890, issued by Britain against Portugal.
The beginning of the British Revolution in March of 1925 meant that the British overseas colonies came under direct pressure from other nations. Both Germany as well as Portugal wanted to connect their African colonies by acquiring British possessions. Germany wished to continue its expansion of Mittelafrika and finally gain a land connection between German South West Africa and German East Africa and the Kongo. Portugal wished to take control of the territories it claimed in the "Pink Map" of 1885, which included Nyasaland and almost all of North and South Rhodesia.
Initially South Africa and Portugal, both members of the Entente and participants in the Weltkrieg as British allies, stepped in under the pretext of safeguarding British colonies from German annexation. The Statthalter of Mittelafrika, Paul von Lettow-Vorbeck, quickly issued a warning that any aggression towards British possessions in Africa would destabilize the region and would not be tolerated. Both Portugal as well as South Africa largely ignored this statement, since it did not have any official backing from Berlin.
The chain of command (and supply) of the British military had shattered with the revolution. Lacking any orders from London the token forces that the United Kingdom had in its African colonies largely stood down when confronted by Portuguese and South African troops in Nyasaland and Bechuanaland respectively. The South Rhodesian colonial administration voted to join South Africa on April 15th as a member state of the union.
Second Ultimatum and German annexations
Fearing a successful Entente landgrab in Southern Africa and after realizing that the British colonial forces did not resist occupation by South Africa and Portugal, Reichskanzler von Tirpitz officially presented King Manuel II of Portugal with the Second Ultimatum. It stated that the British colonies were to be divided along the Zambezi river, from the Caprivi-Strip to the Indian Ocean. This meant that the South African annexations of South Rhodesia and Bechuanaland would be tolerated but that Portugal would have to withdraw from Nyasaland or face military action by the German Empire.
Portugal accepted the ultimatum on June 4th, after realizing that the establishment of the Union of Britain seemed irreversible and knowing that support from the Entente for its cause was highly unlikely. Portugal handed over control of Nyasaland to Mittelafrika by late June.
After the handover of Nyasaland and the annexation of North Rhodesia, Germany was able to connect South West Africa with the rest of Mittelafrika.
Portugal suffered a humiliating loss of prestige by being forced to accept the terms of the Second Ultimatum. In 1926 and as a result of the general discontent following the economic downturn in Portugal as well as the loss of colonial prestige, the Intergalismo Lusitano movement sweeped the elections with its radical platform, and immeditaly set itself on reforming the Portuguese colonial administration.