I don't think there would be one person since there was multiple people involved. But one event that stands out the most to me was the Watergate scandal.
Plessy v. Ferguson allowed separate but to equal known as segregation to become law in the United States.
Answer:
My best guess is that this is related to the Scramble for Africa, where many countries rushed to claim as much territory in Africa as fast as possible.
Explanation:
This is because one, the placard mentions Central Africa, and two, it states that David Livingstone was a traveller.