Nazi Propaganda and Art
One way that Nazi Germany promoted nationalism through art was the promotion of the art they viewed as "ideal"; this was usually art that highlighted Germany as a great power and Germany's beauty and general superiority over the world. (Sauquet) The Nazis themselves promoted this even further with an art exhibit, specifically the "Great German Art Exhibit." The exhibit was opened in 1937, and rotated out different artists that were approved by the Nazis to hang in the exhibit. Hitler was rather obsessive about this exhibit; a good part of its revenue was derived from him purchasing paintings in the exhibit (Kotteder).
The second image is a quintessential look at how art ties into nationalism. Notice how the photos the nazis in the picture are looking at highlight specific ideals: youth and how they represent the future, the impact the war has on their soldiers in their eyes. You can see how one could use art like this to impact the public's mind.