Describe global affairs from the Berlin Conference of 1884 to the fall of the Berlin Wall in 1989. Be sure to consider the role of modernity as you tell the story of European imperialism, WWII, decolonization and Francis Fukuyama’s “End of History.”

Your question focuses on events that took place in Germany and on the issue of imperialism. In my answer I'll therefore try to deal mainly with the global affairs most relevant to those events and on the efforts by European powers to establish control over the rest of the world, which they were then forced to relinquish.
The Berlin conference of 1884 was basically intended to legitimize European plans to establish formal colonies in Africa, rather than just to continue trading with the African nations. As a newly unified country (as of 1871) Germany now came into competition with Britain and France as an imperialistic power. This was the principal factor leading to the outbreak of the Great War in 1914. It was not simply a question of competition for "possession" of the continent of Africa. Germany, by establishing an alliance with the Ottoman Empire, wished to gain control of the trade routes to Asia and thus to encroach upon not only British-French territory (the Suez canal) but also areas claimed by the Russian Empire in central Asia. Britain, France and Russia formed an alliance, the Triple Entente, in opposition to the German plans.
After the carnage of World War I had ended, the financial indemnity imposed upon Germany by the victorious Allies drove Germany into economic chaos. This enabled Hitler and his fanatically racist and chauvinistic Nazi Party to take power in Germany in 1933. The aggressive stance of Germany and its wish to rebuild a German empire based on territory "taken" from it in 1918, coupled with similar aggression by Imperial Japan, led to World War II.
In the aftermath of the Second War, the defeated Germany was re-divided, this time into an East Germany controlled by the Soviet Union, and a democratic West Germany rebuilt largely through United States aid. At the same time, 1945 marked the beginning of the end for European colonialism. The Asian colonial systems of Britain, France and the Netherlands had been collapsed like a house of cards by the Japanese onslaught during the war. Though the Japanese were expelled and defeated, the Asian countries previously colonized would only temporarily revert to European control. The Labour government elected in Britain in 1945 oversaw a plan of granting independence to India and, eventually, virtually all the countries previously constituting the British Empire in Asia and Africa; the other European governments as well divested themselves of their colonies or were forced to give them up over the period from 1945 to the early 1960s.
By the 1980s the Soviet Union was also losing its empire in Europe. The Solidarity Labor Movement in Poland spearheaded the independence of the satellite countries, including Hungary, Czechoslovakia, Romania, Poland, and East Germany. With the fall of the Berlin Wall in November 1989, the road was open to German reunification as a democratic state.
Thus in a period of just over a century, a newly-unified Germany went from an imperialistic power to a defeated one in 1918, then to an aggressor state in Europe from 1933 to 1945, then to a once-again divided country partly under the control of outside powers from 1945 to 1989, and finally to a once-again unified but now democratic country. In the meantime, countries in Asia and Africa which were European colonies 100 years ago are now fully independent.