Which country controlled most of western Africa?

French West Africa existed from 1895 to 1959 and included the areas of modern-day Senegal, Togo, Dahomey, Côte d’Ivoire (the Ivory Coast), Mali, Niger, Guinea, and Mauritania. In the fifteenth century, the Portuguese were the first Europeans to arrive in West Africa, followed by the Dutch, English, and French. The European powers initially traveled along the coast, as they were interested in developing trade ports. As the Transatlantic Slave Trade progressed, slave markets dominated West Africa from the seventeenth through the nineteenth centuries. Other goods such as peanuts and gold increased European activity as well.
As the age of colonialism continued, there was a land grab in Africa leading to the consolidation of French West Africa. 
Due to the abolition of slavery, European interest in West Africa began to decline. However, the European imperial powers would hold on to as many of their colonial territories as they possibly could, even regaining some territories lost during WWII. At this point colonialism had fallen out of fashion, and world leaders encouraged granting independence to colonies. By 1960, all territories of West Africa had gained independence.
https://www.africa.upenn.edu/K-12/French_16178.html