What factor or ideology was most closely related to the need for additional Germany territory?

The ideology most closely related to the need for additional German territory was Pan-Germanism. This was a nationalist ideology that sought to unite all German-speaking people into a single nation. Pan-Germanists believed that Germany needed more territory in order to accommodate its growing population, provide economic resources for its citizens, and secure its borders from potential threats. They also believed that the German nation should have a strong position in Europe and a prominent role in world affairs. These ideas helped to justify the expansionist policies of the German Empire in the late 19th and early 20th centuries.