Question: When did Germany invade the continent where the river serves as drainage for the southwest plain of the Congo located in WWII?

full_context: Document 1: Afrika Korps: The Afrika Korps or German Africa Corps (, DAK ) was the German expeditionary force in Africa during the North African Campaign of World War II. First sent as a holding force to shore up the Italian defense of their African colonies, the formation fought on in Africa, under various appellations, from March 1941 until its surrender in May 1943. The unit's best known commander was Field Marshal Erwin Rommel.
Document 2: Republic of the Congo: Since the country is located on the Equator, the climate is consistent year-round, with the average day temperature being a humid 24 °C (75 °F) and nights generally between 16 °C (61 °F) and 21 °C (70 °F). The average yearly rainfall ranges from 1,100 millimetres (43 in) in south in the Niari Valley to over 2,000 millimetres (79 in) in central parts of the country. The dry season is from June to August while in the majority of the country the wet season has two rainfall maxima: one in March–May and another in September–November.
Document 3: Republic of the Congo: The Republic of the Congo (French: République du Congo), also known as Congo, Congo Republic, West Congo[citation needed], or Congo-Brazzaville, is a country located in Central Africa. It is bordered by five countries: Gabon to the west; Cameroon to the northwest; the Central African Republic to the northeast; the Democratic Republic of the Congo to the east and south; and the Angolan exclave of Cabinda to the southwest.
Document 4: Republic of the Congo: The southwest of the country is a coastal plain for which the primary drainage is the Kouilou-Niari River; the interior of the country consists of a central plateau between two basins to the south and north. Forests are under increasing exploitation pressure.
Document 5: Republic of the Congo: Congo is located in the central-western part of sub-Saharan Africa, along the Equator, lying between latitudes 4°N and 5°S, and longitudes 11° and 19°E. To the south and east of it is the Democratic Republic of Congo. It is also bounded by Gabon to the west, Cameroon and the Central African Republic to the north, and Cabinda (Angola) to the southwest. It has a short coast on the Atlantic Ocean.
Document 6: Mayombe: Mayombe (or Mayumbe) is a geographic area on the western coast of Africa occupied by low mountains extending from the mouth of the Congo River in the south to the Kouilou-Niari River to the north. The area includes parts of the Democratic Republic of the Congo, Angola (Cabinda Province), the Republic of the Congo and Gabon.
Document 7: Geography of Angola: Angola is located on the western Atlantic Coast of Central Africa between Namibia and the Republic of the Congo. It also is bordered by the Democratic Republic of the Congo and Zambia to the east. The country consists of a sparsely watered and somewhat sterile coastal plain extending inland for a distance varying from . Slightly inland and parallel to the coast is a belt of hills and mountains and behind those a large plateau. The total land size is . It has an Exclusive Economic Zone of .
Document 8: Republic of the Congo: The Republic of the Congo's sparse population is concentrated in the southwestern portion of the country, leaving the vast areas of tropical jungle in the north virtually uninhabited. Thus, Congo is one of the most urbanized countries in Africa, with 70% of its total population living in a few urban areas, namely in Brazzaville, Pointe-Noire or one of the small cities or villages lining the 534-kilometre (332 mi) railway which connects the two cities. In rural areas, industrial and commercial activity has declined rapidly in recent years, leaving rural economies dependent on the government for support and subsistence.
Document 9: North African campaign: The North African Campaign of the Second World War took place in North Africa from 10 June 1940 to 13 May 1943. It included campaigns fought in the Libyan and Egyptian deserts (Western Desert Campaign, also known as the Desert War) and in Morocco and Algeria (Operation Torch), as well as Tunisia (Tunisia Campaign).
Document 10: Erwin Rommel: Field Marshal Erwin Rommel (c. 1942) Birth name Johannes Erwin Eugen Rommel Nickname (s) ``The Desert Fox ''(1891 - 11 - 15) 15 November 1891 Heidenheim, Württemberg, German Empire 14 October 1944 (1944 - 10 - 14) (aged 52) Herrlingen, Württemberg, Nazi Germany Buried Cemetery of Herrlingen Allegiance German Empire (1911 -- 1918) Weimar Republic (1919 -- 1933) Nazi Germany (1933 -- 1944) Service / branch Army of Württemberg Reichsheer German Army Years of service 1911 -- 1944 Rank Generalfeldmarschall Commands held 7th Panzer Division Afrika Korps Panzer Army Africa Army Group Africa Army Group B Battles / wars See battles World War I First Battle of the Argonne (1915) Masivul Lesului and Oituz Campaigns (1916 -- 1917) Battle of Caporetto (1917) World War II Invasion of Poland Fall of France Battle of Arras (1940) Siege of Lille (1940) North African Campaign Operation Sonnenblume (1941) Siege of Tobruk (1941) Operation Brevity (1941) Operation Battleaxe (1941) Operation Crusader (1941) Battle of Gazala (1942) Battle of Bir Hakeim (1942) First Battle of El Alamein (1942) Battle of Alam Halfa (1942) Second Battle of El Alamein (1942) Battle of El Agheila (1942) Battle of the Kasserine Pass (1943) Battle of Medenine (1943) Battle of Normandy (1944) Awards Iron Cross, First Class Pour le Mérite Knight's Cross of the Iron Cross with Oak Leaves, Swords and Diamonds Spouse (s) Lucia Maria Mollin (m. 1916) Relations Manfred Rommel (1928 -- 2013), son Gertrud Stemmer (1913 -- 2000), daughter Signature
Document 11: Yumbi: Yumbi is a town and territory in Plateaux District of Bandundu Province in the Democratic Republic of the Congo. It lies on the eastern bank of the Congo River between Bolobo and Lukolela.
Document 12: Mitumba Mountains: The Mitumba Mountain range stretches along the Western Rift Valley in Eastern Congo (DRC), west of lake Tanganyika. The two main peaks, Mount Kahuzi (3,308 m) and Mount Biéga (2,790 m) are extinct volcanoes.
Document 13: First Battle of El Alamein: The First Battle of El Alamein (1 -- 27 July 1942) was a battle of the Western Desert Campaign of the Second World War, fought in Egypt between Axis forces (Germany and Italy) of the Panzer Army Africa (Panzerarmee Afrika, which included the Afrika Korps) (Field Marshal (Generalfeldmarschall) Erwin Rommel) and Allied (British Imperial and Commonwealth) forces (Britain, British India, Australia, South Africa and New Zealand) of the Eighth Army (General Claude Auchinleck).
Document 14: North African campaign: Fighting in North Africa started with the Italian declaration of war on 10 June 1940. On 14 June, the British Army's 11th Hussars (assisted by elements of the 1st Royal Tank Regiment, 1st RTR) crossed the border from Egypt into Libya and captured the Italian Fort Capuzzo. This was followed by an Italian counter-offensive into Egypt and the capture of Sidi Barrani in September 1940 and again in December 1940 following a British Commonwealth counteroffensive, Operation Compass. During Operation Compass, the Italian 10th Army was destroyed and the German Afrika Korps -- commanded by Erwin Rommel, who later became known as ``The Desert Fox ''-- was dispatched to North Africa in February 1941 during Operation Sonnenblume to reinforce Italian forces in order to prevent a complete Axis defeat.
Document 15: Congo River: Railways now bypass the three major falls, and much of the trade of Central Africa passes along the river, including copper, palm oil (as kernels), sugar, coffee, and cotton. The river is also potentially valuable for hydroelectric power, and the Inga Dams below Pool Malebo are first to exploit the Congo river.
ground_truth: in February 1941
sub_queries: Which river serves as drainage for the southwest plain of the Congo? Answer: Kouilou-Niari River
Kouilou-Niari River >> continent Answer: Africa
when did germany invade Africa in world war 2 Answer: in February 1941