The often-told story is that European Imperialism towards Africa was caused by a thirst to exploit Africa's riches. And that is lasted for centuries, while in truth it only lasted some 80 years, from around 1880 until 1960.Strangely enough, in reality the cause was slavery. Notby the white people, who by then (around 1880/90) already had long abandoned it, but the slavery of Africans by Africans. It was the European missionaries who whipped up public support to convince their often very reluctant Governments to take action against African rulers who refused to abolish slavery in their lands.The proclaimed 'riches' could already be had by setting up trading posts along Africa's coast and by informing the local rulers that the European traders were prepared to pay good money (well, sort of...) for whatever they had on offer. And that had already been happening since the early 16th century.Truth be told, once the forced takeovers started - and by the way, the Europeans' first action indeed was abolishing slavery - Britain realized that by colonizing all of East Africa they could control and safeguard the passage to India and other Far East posessions. France (always keen on their national 'glory') realized that they could enhance this 'glory' by having a colonial Empire. And the same feelings of national prestige caused a few other countries to claim parts of Africa. And of course, instead of buying goods from local rulers the Europeans could now produce and export them through their own companies.The form of imperialism was much the same in sub-Sahara Africa. There were very few European volunteers for a career in African government, if only because many of them died of tropical diseases within months of arrival. So the usual form was: a limited number of European administrators only in key Government posts; a local tribe was selected and trained that showed aptitude for western-style administration; and then all lower Government post were filled by local people under a usually white Director.In North Africa, in countries like Morocco and Egypt, a well-organized form of local rule and administration was already in place. Here, colonization took place by leaving the local rulers and administrators on their posts, but making treaties with these countries in which a European country effectively took over the the control of the army, the finances and of foreign policy.