Portugal during World War I

Tensions between Germany and Portugal also arose as a result of German U-boat warfare, which sought to blockade the United Kingdom, at the time the most important market for Portuguese products.

Ultimately this led to the confiscation of German ships interned in Portuguese ports in 1916, to which Germany reacted by declaring war on 9 March 1916.

In total, from 1916 to 1918, about 91 Portuguese ships were sunk and 5 damaged by German U-boats, causing at least 170 casualties.

[1] About 12,000 Portuguese troops died during World War I, including Africans who served in its armed forces on the colonial front.

During this battle, one of the most courageous acts in Portuguese military history was perpetrated, as Private Aníbal Milhais (also known as "Soldado Milhões" ["A Soldier as good as a million others" in his commanding officer's words]) defended the retreating Allied forces with nothing but his machine gun, allowing them to fall back and regroup.