German campaign in Angola Before the official declaration of war between Germany and Portugal ( March 1916 ) , German and Portuguese troops clashed several times on the border between German South West Africa and Portuguese Angola . The Germans won most of these clashes and were able to occupy the Humbe region of southern Angola until Portuguese control was restored a few days before the British campaign out of South Africa defeated the Germans . Background . From 1911 until July 1914 German and British Empires secretly negotiated about possible dismemberment of Portuguese Angola ; . In such a case most of the land would fall into the hands of the Germans . " Angola - Bund " , founded in 1912 , was the German organization promoting the takeover . Even before World War I started ( September 1914 ) , the Portuguese government had sent reinforcements to the southern border of Angola . After the war broke out , the border between German South West Africa and Angola remained open . The Germans hoped they would be able to supply food and possibly even arms through it . However , the Portuguese colonial government was rather hostile and attempted to thwart all possible trade . A few German nationals in Angola were interned . The campaign . The campaign in southern Portuguese Angola took place before a formal state of war had been declared between Germany and Portugal . The clashes occurred between October 1914 and July 1915 ; Germany didn ' t declare war on Portugal until 9 March 1916 . Due to the possibility of an attack from German Southwest Africa , Portuguese forces in southern Angola were reinforced by a military expedition led by Lieutenant - Colonel Alves Roçadas , which arrived at Moçâmedes on 1 October 1914 . Since mid - 1914 , there had been several incidents between Portuguese and German troops . The first serious one was the Naulila incident on 19 October , in which 3 German officers , heading a military column which had entered Angola without permission from the Portuguese authorities , were killed by Portuguese troops . On 31 October , German troops armed with machine guns launched a surprise attack on the small Portuguese outpost at Cuangar , killing 2 officers , 1 sergeant , 5 soldiers and 1 civilian . The attack became known as the " Cuangar Massacre " . On 18 December the largest clash of the campaign occurred . A German force of 2 , 000 men under the command of Major Victor Franke attacked Portuguese forces positioned at Naulila . After a stubborn resistance , the Portuguese were forced to withdraw towards the Humbe region , with 69 soldiers dead , among them 3 officers , 76 wounded , among them 1 officer , and 79 prisoners , among them 3 officers , while the Germans had 12 soldiers dead and 30 wounded , among them 10 officers . After the explosion of the munitions magazine at Forte Roçadas base the Portuguese also left the Humbe , withdrawing farther north . On 7 July 1915 , Portuguese forces under the command of General Pereira d ' Eça reoccupied the Humbe region . Two days later German forces in South West Africa surrendered , ending the South - West Africa Campaign . Until September 1915 , the Portuguese continued fighting in southern Angola against local groups who resisted colonial occupation , and who in part had received arms from the Germans .