On the outbreak of World War I, Portugal had proclaimed its adhesion to the English alliance (Aug. 7, 1914) and on November 23 committed itself to military operations against Germany. On September 11 the first expedition left to reinforce the African colonies, and there was fighting in northern Mozambique, on the Tanganyika frontier, and in southern Angola, on the frontier of German South West Africa. In compliance with a request from Britain, in February 1916 Portugal seized German ships lying in Portuguese ports, and Germany declared war on Portugal (March 9). A Portuguese expeditionary force went to Flanders in 1917, under General Fernando Tamagnini de Abreu, and on April 9, 1918, the Germans mounted a major attack in the Battle of the Lys. Although the Allies won the war, and Portugal's colonies were safeguarded, the 0.75 percent of the war indemnity paid by Germany to Portugal was scant compensation for the heavy costs incurred, both in the field and at home: the casualties of the African campaigns and the western front; the alienation of a portion of the army officer corps; crippling war debts to Britain; intense inflation; and a scarcity of food and fuel.
короче, "верные союзническому долгу" - хотя немцы до ПМВ замахивались на португальские колонии
