Answer:
Germany was defeted in WWI, poor, and humiliated. The rise of nationalism was a natural consequence to this happenings.
Step-by-step explanation:
Germany was defeated in The First World War, and was blamed for starting the war.
After the peace treaty of Versailles, the Allies wanted Germany to pay the war reparations, to cut the army, and accept total defeat.
In the 1920's Germany found itself in one of the biggest economic crises of all times. Poverty was inevitable in a time of extreme inflation. The people were desperate and angry.
Then on the political scene appeared The National Socialist German Workers' Party (The Nazi Party of Adolf Hitler), which ideas were to speak to the poor people of Germany, and to defend the integrity of Germany and the Germans. To make Germany strong again, and to rise after such defeats.