Question: Where was the German campaign in the country where Cassinga is located?

full_context: Document 1: History of Angola: Angola is a country in southwestern Africa. The country's name derives from the Kimbundu word for king. It was first settled by San hunter - gatherer societies before the northern domains came under the rule of Bantu states such as Kongo and Ndongo. From the 15th century, Portuguese colonists began trading, and a settlement was established at Luanda during the 16th century. Portugal annexed territories in the region which were ruled as a colony from 1655, and Angola was incorporated as an overseas province of Portugal in 1951. After the Angolan War of Independence which ended with an army mutiny and leftist coup in Lisbon, Angola's independence was achieved on November 11, 1975 through the Alvor Agreement. After independence, Angola later entered a period of civil war that lasted up until 2002.
Document 2: Germans: In 1866, the feud between Austria and Prussia finally came to a head. There were several reasons behind this war. As German nationalism grew strongly inside the German Confederation and neither could decide on how Germany was going to be unified into a nation-state. The Austrians favoured the Greater Germany unification but were not willing to give up any of the non-German-speaking land inside of the Austrian Empire and take second place to Prussia. The Prussians however wanted to unify Germany as Little Germany primarily by the Kingdom of Prussia, whilst excluding Austria. In the final battle of the German war (Battle of Königgrätz) the Prussians successfully defeated the Austrians and succeeded in creating the North German Confederation.
Document 3: British Empire: Britain's fears of war with Germany were realised in 1914 with the outbreak of the First World War. Britain quickly invaded and occupied most of Germany's overseas colonies in Africa. In the Pacific, Australia and New Zealand occupied German New Guinea and Samoa respectively. Plans for a post-war division of the Ottoman Empire, which had joined the war on Germany's side, were secretly drawn up by Britain and France under the 1916 Sykes–Picot Agreement. This agreement was not divulged to the Sharif of Mecca, who the British had been encouraging to launch an Arab revolt against their Ottoman rulers, giving the impression that Britain was supporting the creation of an independent Arab state.
Document 4: Gusevogoroskoye mine: The Gusevogoroskoye mine is a large iron mine located in western Russia in the Sverdlovsk Oblast. Gusevogoroskoye represents one of the largest iron ore reserves in Russia and in the world having estimated reserves of 2.82 billion tonnes of ore grading 15.7% iron metal.
Document 5: Military history of South Africa during World War II: On 4 September 1939, the United Party caucus refused to accept Hertzog's stance of neutrality in World War II and deposed him in favour of Smuts. Upon becoming Prime Minister, Smuts declared South Africa officially at war with Germany and the Axis. He immediately set about fortifying South Africa against any possible German sea invasion because of South Africa's global strategic importance controlling the long sea route around the Cape of Good Hope.
Document 6: Portugal: In the 20th century, Portugal engaged in two major conflicts: World War I and the Portuguese Colonial War (1961–1974). After the end of the Portuguese Empire in 1975, the Portuguese Armed Forces have participated in peacekeeping missions in East Timor, Bosnia, Kosovo, Afghanistan, Somalia, Iraq (Nasiriyah) and Lebanon. Portugal also conducted several independent unilateral military operations abroad, as were the cases of the interventions of the Portuguese Armed Forces in Angola in 1992 and in Guinea-Bissau in 1998 with the main objectives of protecting and withdrawing of Portuguese and foreign citizens threatened by local civil conflicts.
Document 7: Northern Seven Years' War: 1762 brought two new countries into the war. Britain declared war against Spain on 4 January 1762; Spain reacted by issuing their own declaration of war against Britain on 18 January. Portugal followed by joining the war on Britain's side. Spain, aided by the French, launched an invasion of Portugal and succeeded in capturing Almeida. The arrival of British reinforcements stalled a further Spanish advance, and the Battle of Valencia de Alcántara saw British-Portuguese forces overrun a major Spanish supply base. The invaders were stopped on the heights in front of Abrantes (called the pass to Lisbon) where the Anglo-Portuguese were entrenched. Eventually the Anglo-Portuguese army, aided by guerrillas and practicing a scorched earth strategy, chased the greatly reduced Franco-Spanish army back to Spain, recovering almost all the lost towns, among them the Spanish headquarters in Castelo Branco full of wounded and sick that had been left behind.
Document 8: Agbaja mine: The Agbaja mine is a large iron mine located in central Nigeria in the Kogi State. Agbaja represents one of the largest iron ore reserves in Nigeria and in the world having estimated reserves of 1.25 billion tonnes of ore grading 48% iron metal.
Document 9: Cassinga mine: The Cassinga mine is a large iron mine located in south-western Angola in Huíla Province. Cassinga represents one of the largest iron ore reserves in Angola and in the world having estimated reserves of 1 billion tonnes of ore grading 30% iron metal.
Document 10: History of Germany during World War I: During World War I, the German Empire was one of the Central Powers that lost the war. It began participation in the conflict after the declaration of war against Serbia by its ally, Austria - Hungary. German forces fought the Allies on both the eastern and western fronts, although German territory itself remained relatively safe from widespread invasion for most of the war, except for a brief period in 1914 when East Prussia was invaded. A tight blockade imposed by the Royal Navy caused severe food shortages in the cities, especially in the winter of 1916 -- 17, known as the Turnip Winter. At the end of the war, Germany's defeat and widespread popular discontent triggered the German Revolution of 1918 -- 19 which overthrew the monarchy and established the Weimar Republic.
Document 11: Kiruna Mine: The Kiruna mine is the largest and most modern underground iron ore mine in the world. The mine is located in Kiruna in Norrbotten County, Lapland, Sweden. The mine which is owned by Luossavaara-Kiirunavaara AB (LKAB), a large Swedish mining company, has an annual production capacity of over 26 million tonnes of iron ore. In 2008 the mine produced 27.5 million tonnes of iron ore. The Kiruna mine has an ore body which is long, to thick and reaching a depth of up to . Since mining began at the site in 1898, the mine has produced over 950 million tonnes of ore.
Document 12: Chara mine: The Chara mine is a large iron mine located in southern Russia in the Zabaykalsky Krai. Chara represents one of the largest iron ore reserves in Russia and in the world having estimated reserves of 8 billion tonnes of ore grading 30% iron metal.
Document 13: Yuanjiachun mine: The Yuanjiachun mine is a large iron mine located in northern China. Yuanjiachun represents one of the largest iron ore reserves in China and in the world having estimated reserves of 895 million tonnes of ore grading 32.7% iron metal.
Document 14: 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.
Document 15: Tarkwa mine: The Tarkwa mine is one of the largest gold mines in the Ghana and in the world. The mine is located in the south-west of the country in the Western Region. The mine has estimated reserves of 15.1 million oz of gold.
ground_truth: Portuguese Angola
sub_queries: Cassinga >> country Answer: Angola
German campaign in Angola >> location Answer: Portuguese Angola