Answer:
The event that required European nations to inform others when claiming a new African territory was the Berlin Conference.
Step-by-step explanation:
The Berlin Conference marked the European organization and collaboration for the division of Africa. It began on November 15, 1884 in Berlin and ended on February 26, 1885. On the initiative of Portugal and organized by Otto von Bismarck, Germany, Austria-Hungary, Belgium, Denmark, the Ottoman Empire, Spain, France, Great Britain, Italy, the Netherlands, Portugal, Russia, Sweden-Norway and the United States participated. An earlier conference started the debate on the partition of the Congo. The Berlin Conference resulted mainly in enacting the official rules of colonization in Africa. The direct impact on settlements was a European wave of treaty signing.