The European struggled to est

The French and the British fought against the Dutch and they took control on West African trade. Later on with civil problem inside France, the British took control in West Africa
The geographic areas that the British settled in on that time, was the whole West African coast, besides south and east.
One of the British’s colonies was Nigeria. The first idea that the British had was to open markets for manufactured goods in West Africa and expands commerce in palm oil. But the main reason changed and the British started exploring Nigeria, because of the slave trade. The slave trade devastated Nigeria during three centuries (1500 to mid 1800).
Besides the slave trade Nigeria, the British were focused in take advantage of Nige

I am not sure how many people came over Nigeria that time. But since the British had power enough to take over the West Coast, I guess there were a lot of them there.
I believe the difference between America and Nigeria colonization was that in American colonization the British were more interested in expanding land and finding a way to extend trade to Asia. In Nigeria they were more interested in slave and crops trade. They would use these slaves to increase their production and become wealthier.